fix(net): check if var is empty instead of matching strings

Author: ezrizhu

try

@@ -233,10 +233,10 @@ EOF
     # --pid: create a new process namespace (needed fr procfs to work right)
     # --fork: necessary if we do --pid
     #         "Creation of a persistent PID namespace will fail if the --fork option is not also specified."
-    if [ "$EXTRA_NS" = "net" ]; then
-        unshare --mount --map-root-user --user --pid --fork --net "$mount_and_execute"
-    else
+    if [ -z "$EXTRA_NS" ]; then
         unshare --mount --map-root-user --user --pid --fork "$mount_and_execute"
+    else
+        unshare --mount --map-root-user --user --pid --fork --net "$mount_and_execute"
     fi
     TRY_EXIT_STATUS=$?