diff --git a/.github/workflows/nix-action-8.19.yml b/.github/workflows/nix-action-8.19.yml
index 27378388f..24d01ee31 100644
--- a/.github/workflows/nix-action-8.19.yml
+++ b/.github/workflows/nix-action-8.19.yml
@@ -36,12 +36,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (coq)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.19\" --argstr job \"coq\" \\\n   --dry-run 2> err > out || (touch fail;
+        true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target coq
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.19\" --argstr job \"coq\" \\\n   --dry-run 2>&1 > /dev/null)\n
-        echo $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\" | sed \"\
-        s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: Building/fetching current CI target
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.19" --argstr
@@ -84,12 +90,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.19\" --argstr job \"mathcomp\" \\\n   --dry-run 2> err > out || (touch
+        fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.19\" --argstr job \"mathcomp\" \\\n   --dry-run 2>&1 > /dev/null)\n
-        echo $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\" | sed \"\
-        s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.19" --argstr
@@ -169,12 +181,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-analysis)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.19\" --argstr job \"mathcomp-analysis\" \\\n   --dry-run 2> err > out
+        || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-analysis
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.19\" --argstr job \"mathcomp-analysis\" \\\n   --dry-run 2>&1 >
-        /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.19" --argstr
@@ -237,12 +255,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-analysis-single)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.19\" --argstr job \"mathcomp-analysis-single\" \\\n   --dry-run 2> err
+        > out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-analysis-single
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.19\" --argstr job \"mathcomp-analysis-single\" \\\n   --dry-run
-        2>&1 > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep
-        \"built:\" | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.19" --argstr
@@ -315,12 +339,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-analysis-stdlib)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.19\" --argstr job \"mathcomp-analysis-stdlib\" \\\n   --dry-run 2> err
+        > out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-analysis-stdlib
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.19\" --argstr job \"mathcomp-analysis-stdlib\" \\\n   --dry-run
-        2>&1 > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep
-        \"built:\" | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.19" --argstr
@@ -379,12 +409,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-classical)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.19\" --argstr job \"mathcomp-classical\" \\\n   --dry-run 2> err > out
+        || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-classical
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.19\" --argstr job \"mathcomp-classical\" \\\n   --dry-run 2>&1
-        > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.19" --argstr
@@ -444,12 +480,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-experimental-reals)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.19\" --argstr job \"mathcomp-experimental-reals\" \\\n   --dry-run 2>
+        err > out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-experimental-reals
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.19\" --argstr job \"mathcomp-experimental-reals\" \\\n   --dry-run
-        2>&1 > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep
-        \"built:\" | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.19" --argstr
@@ -509,12 +551,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-reals)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.19\" --argstr job \"mathcomp-reals\" \\\n   --dry-run 2> err > out ||
+        (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-reals
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.19\" --argstr job \"mathcomp-reals\" \\\n   --dry-run 2>&1 > /dev/null)\n
-        echo $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\" | sed \"\
-        s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.19" --argstr
@@ -570,12 +618,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-reals-stdlib)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.19\" --argstr job \"mathcomp-reals-stdlib\" \\\n   --dry-run 2> err >
+        out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-reals-stdlib
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.19\" --argstr job \"mathcomp-reals-stdlib\" \\\n   --dry-run 2>&1
-        > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.19" --argstr
diff --git a/.github/workflows/nix-action-8.20.yml b/.github/workflows/nix-action-8.20.yml
index c3f3dd587..97b05d9fc 100644
--- a/.github/workflows/nix-action-8.20.yml
+++ b/.github/workflows/nix-action-8.20.yml
@@ -36,12 +36,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (coq)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.20\" --argstr job \"coq\" \\\n   --dry-run 2> err > out || (touch fail;
+        true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target coq
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.20\" --argstr job \"coq\" \\\n   --dry-run 2>&1 > /dev/null)\n
-        echo $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\" | sed \"\
-        s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: Building/fetching current CI target
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.20" --argstr
@@ -84,12 +90,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.20\" --argstr job \"mathcomp\" \\\n   --dry-run 2> err > out || (touch
+        fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.20\" --argstr job \"mathcomp\" \\\n   --dry-run 2>&1 > /dev/null)\n
-        echo $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\" | sed \"\
-        s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.20" --argstr
@@ -169,12 +181,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-analysis)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.20\" --argstr job \"mathcomp-analysis\" \\\n   --dry-run 2> err > out
+        || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-analysis
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.20\" --argstr job \"mathcomp-analysis\" \\\n   --dry-run 2>&1 >
-        /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.20" --argstr
@@ -237,12 +255,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-analysis-single)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.20\" --argstr job \"mathcomp-analysis-single\" \\\n   --dry-run 2> err
+        > out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-analysis-single
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.20\" --argstr job \"mathcomp-analysis-single\" \\\n   --dry-run
-        2>&1 > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep
-        \"built:\" | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.20" --argstr
@@ -315,12 +339,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-analysis-stdlib)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.20\" --argstr job \"mathcomp-analysis-stdlib\" \\\n   --dry-run 2> err
+        > out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-analysis-stdlib
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.20\" --argstr job \"mathcomp-analysis-stdlib\" \\\n   --dry-run
-        2>&1 > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep
-        \"built:\" | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.20" --argstr
@@ -379,12 +409,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-classical)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.20\" --argstr job \"mathcomp-classical\" \\\n   --dry-run 2> err > out
+        || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-classical
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.20\" --argstr job \"mathcomp-classical\" \\\n   --dry-run 2>&1
-        > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.20" --argstr
@@ -444,12 +480,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-experimental-reals)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.20\" --argstr job \"mathcomp-experimental-reals\" \\\n   --dry-run 2>
+        err > out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-experimental-reals
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.20\" --argstr job \"mathcomp-experimental-reals\" \\\n   --dry-run
-        2>&1 > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep
-        \"built:\" | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.20" --argstr
@@ -509,12 +551,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-reals)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.20\" --argstr job \"mathcomp-reals\" \\\n   --dry-run 2> err > out ||
+        (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-reals
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.20\" --argstr job \"mathcomp-reals\" \\\n   --dry-run 2>&1 > /dev/null)\n
-        echo $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\" | sed \"\
-        s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.20" --argstr
@@ -570,12 +618,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-reals-stdlib)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"8.20\" --argstr job \"mathcomp-reals-stdlib\" \\\n   --dry-run 2> err >
+        out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-reals-stdlib
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"8.20\" --argstr job \"mathcomp-reals-stdlib\" \\\n   --dry-run 2>&1
-        > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "8.20" --argstr
diff --git a/.github/workflows/nix-action-master.yml b/.github/workflows/nix-action-master.yml
index 81711ae1c..cace87f5d 100644
--- a/.github/workflows/nix-action-master.yml
+++ b/.github/workflows/nix-action-master.yml
@@ -36,12 +36,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (coq)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"coq\" \\\n   --dry-run 2> err > out || (touch fail;
+        true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target coq
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"coq\" \\\n   --dry-run 2>&1 > /dev/null)\n
-        echo $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\" | sed \"\
-        s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: Building/fetching current CI target
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -85,12 +91,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (coq-elpi)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"coq-elpi\" \\\n   --dry-run 2> err > out || (touch
+        fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target coq-elpi
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"coq-elpi\" \\\n   --dry-run 2>&1 > /dev/null)\n
-        echo $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\" | sed \"\
-        s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -142,12 +154,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (hierarchy-builder)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"hierarchy-builder\" \\\n   --dry-run 2> err > out
+        || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target hierarchy-builder
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"hierarchy-builder\" \\\n   --dry-run 2>&1
-        > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -200,12 +218,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"mathcomp\" \\\n   --dry-run 2> err > out || (touch
+        fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"mathcomp\" \\\n   --dry-run 2>&1 > /dev/null)\n
-        echo $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\" | sed \"\
-        s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -287,12 +311,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-analysis)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"mathcomp-analysis\" \\\n   --dry-run 2> err > out
+        || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-analysis
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"mathcomp-analysis\" \\\n   --dry-run 2>&1
-        > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -359,12 +389,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-analysis-single)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"mathcomp-analysis-single\" \\\n   --dry-run 2> err
+        > out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-analysis-single
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"mathcomp-analysis-single\" \\\n   --dry-run
-        2>&1 > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep
-        \"built:\" | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -438,12 +474,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-analysis-stdlib)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"mathcomp-analysis-stdlib\" \\\n   --dry-run 2> err
+        > out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-analysis-stdlib
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"mathcomp-analysis-stdlib\" \\\n   --dry-run
-        2>&1 > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep
-        \"built:\" | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -502,12 +544,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-bigenough)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"mathcomp-bigenough\" \\\n   --dry-run 2> err > out
+        || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-bigenough
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"mathcomp-bigenough\" \\\n   --dry-run 2>&1
-        > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -560,12 +608,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-classical)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"mathcomp-classical\" \\\n   --dry-run 2> err > out
+        || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-classical
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"mathcomp-classical\" \\\n   --dry-run 2>&1
-        > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -627,12 +681,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-experimental-reals)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"mathcomp-experimental-reals\" \\\n   --dry-run 2>
+        err > out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-experimental-reals
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"mathcomp-experimental-reals\" \\\n   --dry-run
-        2>&1 > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep
-        \"built:\" | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -691,12 +751,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-finmap)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"mathcomp-finmap\" \\\n   --dry-run 2> err > out
+        || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-finmap
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"mathcomp-finmap\" \\\n   --dry-run 2>&1 >
-        /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -749,12 +815,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-reals)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"mathcomp-reals\" \\\n   --dry-run 2> err > out ||
+        (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-reals
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"mathcomp-reals\" \\\n   --dry-run 2>&1 >
-        /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\"\
-        \ | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -811,12 +883,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (mathcomp-reals-stdlib)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"mathcomp-reals-stdlib\" \\\n   --dry-run 2> err
+        > out || (touch fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target mathcomp-reals-stdlib
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"mathcomp-reals-stdlib\" \\\n   --dry-run
-        2>&1 > /dev/null)\necho $nb_dry_run\necho status=$(echo $nb_dry_run | grep
-        \"built:\" | sed \"s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
@@ -871,12 +949,18 @@ jobs:
         authToken: ${{ secrets.CACHIX_AUTH_TOKEN }}
         extraPullNames: coq, coq-community
         name: math-comp
+    - id: stepGetDerivation
+      name: Getting derivation for current job (stdlib)
+      run: "NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr bundle
+        \"master\" --argstr job \"stdlib\" \\\n   --dry-run 2> err > out || (touch
+        fail; true)\n"
+    - name: Error reporting
+      run: "echo \"out=\"; cat out\necho \"err=\"; cat err\n"
+    - name: Failure check
+      run: if [ -e fail ]; then exit 1; else exit 0; fi;
     - id: stepCheck
-      name: Checking presence of CI target stdlib
-      run: "nb_dry_run=$(NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link \\\n   --argstr
-        bundle \"master\" --argstr job \"stdlib\" \\\n   --dry-run 2>&1 > /dev/null)\n
-        echo $nb_dry_run\necho status=$(echo $nb_dry_run | grep \"built:\" | sed \"\
-        s/.*/built/\") >> $GITHUB_OUTPUT\n"
+      name: Checking presence of CI target for current job
+      run: (echo -n status=; cat out | grep "built:" | sed "s/.*/built/") >> $GITHUB_OUTPUT
     - if: steps.stepCheck.outputs.status == 'built'
       name: 'Building/fetching previous CI target: coq'
       run: NIXPKGS_ALLOW_UNFREE=1 nix-build --no-out-link --argstr bundle "master"
diff --git a/.nix/config.nix b/.nix/config.nix
index 935d36a35..25a13ce7a 100644
--- a/.nix/config.nix
+++ b/.nix/config.nix
@@ -59,16 +59,17 @@ in
     ssprove.job = false;
   };
 
-  bundles."master" = { coqPackages = common-bundle // {
+  bundles."master".coqPackages = common-bundle // {
     coq.override.version = "master";
     stdlib.override.version = "master";
     coq-elpi.override.version = "master";
+    coq-elpi.override.elpi-version = "2.0.7";
     hierarchy-builder.override.version = "master";
     mathcomp.override.version = "master";
     mathcomp-bigenough.override.version = "master";
     mathcomp-finmap.override.version = "master";
     ssprove.job = false;
-  }; ocamlPackages = { elpi.override.version = "2.0.6"; }; };
+  };
 
   ## Cachix caches to use in CI
   ## Below we list some standard ones
diff --git a/.nix/coq-nix-toolbox.nix b/.nix/coq-nix-toolbox.nix
index eb2e2bb9f..6062e55ae 100644
--- a/.nix/coq-nix-toolbox.nix
+++ b/.nix/coq-nix-toolbox.nix
@@ -1 +1 @@
-"fb3515feec422e546de863ad0101e2a51ec9b8db"
+"78d95509824be9e3339c1c0ee19f9c085f32b23e"