fix(ci): prevent PYTHONHOME leak in Windows nox sub-sessions#559
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Pull request overview
Updates the Windows CI test runner composite action to prevent PYTHONHOME (set by uv run for Python 3.14) from leaking into nox sub-sessions running other Python versions.
Changes:
- Unsets
PYTHONHOMEimmediately before executingmake $MAKE_TARGETin therun-testscomposite action.
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…dows On Windows, uv run sets PYTHONHOME to the managed Python 3.14 install directory. This leaks into nox sub-sessions for older Python versions (3.11-3.13), causing them to load 3.14's stdlib and crash at startup. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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arne-aignx
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Apr 23, 2026
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Why?
Windows CI fails for Python 3.11, 3.12, and 3.13 because
uv runsetsPYTHONHOMEto the managed Python 3.14 install directory when launching nox. This leaks into pytest sub-processes for older Python versions, causing them to load 3.14's stdlib and crash at startup (SyntaxError on 3.11; fatalinit_import_siteon 3.12/3.13).How?
On Windows only, strip
PYTHONHOMEfrom the session's subprocess environment in_run_test_suitebefore any pytest process is spawned. The fix is guarded byplatform.system() == "Windows"to avoid affecting coverage collection on Linux/macOS.