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fix(util): tolerate deleted temporary environment variables - #2340
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Byron merged 2 commits intoNov 5, 2026
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When a `patch_env()` body deletes a variable that was initially absent, cleanup raises `KeyError` and can mask an exception from the body. Use `os.environ.pop(name, None)` to restore absence idempotently while preserving restoration of existing values. Add 18 regression cases for absent, empty and populated original values, keep/replace/delete body mutations and normal/exceptional exits. The focused CLI-backend tests changed from 2 failed and 16 passed to 18 passed. Ruff lint/format and `git diff --check` passed. The full suite was not run because its required `GixPython` Windows wheel was unavailable. Agent-Model: unknown
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🟢 Approval recommended
No active review issues are reported for the change that prevents environment cleanup from masking context-body exceptions.
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What changed in this PR
This PR makes GitPython’s patch_env() cleanup tolerate deletion of a temporary environment variable, preventing a cleanup KeyError from masking an exception raised inside the context.
Changes:
- Use
os.environ.pop(name, None)when restoring an originally absent variable. - Add 18 regression cases covering original values, temporary-variable mutations, and normal or exceptional exits.
Review by GitHub Copilot.
| File | Description |
|---|---|
test/test_patch_env.py |
Tests environment restoration and preservation of context-body exceptions. |
git/util.py |
Makes cleanup safe when an originally absent variable has already been deleted. |
Review effort: Balanced
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patch_env()raisesKeyErroron exit if its variable was originally absent and the context body deletes it. If the body also raises an exception, the cleanup error masks that exception.Use
os.environ.pop(name, None)when restoring an originally absent variable. Add 18 regression cases covering absent, empty and populated original values; unchanged, replaced and deleted temporary values; and normal and exceptional exits.Motivation: this was discovered while inspecting GitPython with a user seeking their first small Python contribution to Git tooling on Windows. The goal is to make the environment helper's restoration behavior consistent when a caller changes the temporary variable. Codex prepared the implementation, tests and this description.
Validation on Windows, Python 3.13.17 and Git 2.56.0.windows.4:
GIT_PYTHON_BACKEND=cliandpython -m pytest --noconftest -o addopts='' test/test_patch_env.py -q --tb=short.git diff --checkpassed.The full suite and its conftest hooks were not run. Installing the test extra with binary-only GixPython failed because no compatible Windows wheel for GixPython 0.3.0 was available. The focused tests do not use repository fixtures or Gix.