- Updates _check_bash_state to not short-circuit on the first unusable
bash candidate on Windows, ensuring a working fallback is found if present.
- Clears bash detection cache in unittest setUp/tearDown rather than just
relying on a pytest fixture, covering native unittest runners.
Adds a conftest.py pytest fixture to explicitly clear the lru_cache for bash
detection, addressing the monkeypatching hazard in a way that doesn't rely
solely on comments. (Note: CI currently runs python -m unittest, but this
keeps local pytest runners safe.)
Also updates the bash check to run the execution probe directly inside the
cached _check_bash_state, exposing the difference between 'no bash found'
and 'bash present but execution failed' directly to the unittest skip reason.
Moves get_bash_executable and require_bash into a shared module so their
lru_cache state is per-session rather than per-test-module. Also adds a
comment regarding monkeypatching since lru_cache will silently drop changes
to os.environ if it has already been populated.
Closes follow-up items from PR review.
Gracy769