build sdist script

ci/python_build_sdist.sh

@@ -0,0 +1,27 @@
+#!/usr/bin/env bash
+
+# build the sdist file, and try installing it
+
+set -euo pipefail
+
+BASE=$(pwd)/build/
+
+mkdir -p "$BASE"
+
+VENV="$BASE/venv-python-sdist/"
+if [[ ! -d "$VENV" ]]; then
+    python3 -mvenv "$VENV"
+fi
+BIN="$VENV/bin/"
+
+set +u  # ignore missing variables in activation script
+source "$BIN/activate"
+set -u
+
+"$BIN/pip" install -U setuptools pip twine
+"$BIN/python" setup.py sdist
+
+ls -al dist
+
+cd "$VENV"
+"$BIN/pip" --verbose install ../../dist/*.tar.gz