`set -o pipefail` at the top of tests.sh combined with `find ... | head -1`
is a silent-killer pattern. When `find` produces lots of matches (e.g.
when uv has installed dozens of third-party packages with test_*.py
files under .venv), `head -1` reads its single line and closes the pipe.
`find` writes again, gets SIGPIPE, exits 141. pipefail propagates 141.
`set -e` fires. tests.sh exits 141 before printing `-- Python (pytest ...) --`
or any other output. run-all.sh records `tests: failed` with no
indication of WHY.
Reproduced directly:
bash -c 'set -euo pipefail; x=$(find <large-tree> -name "test_*.py" -o -name "*_test.py" | head -1); echo "got: $x"'
exit=141 # "got:" never prints
Fix: replace `| head -1` with `-print -quit` so find stops itself
after the first match instead of getting cut off mid-write. As a free
bonus, also prune the well-known noise dirs (.venv, .git, etc.) so the
probe doesn't even consider third-party test files in the first place —
this keeps the probe fast on dense trees and avoids matching
@pytest.fixture-decorated files in installed packages.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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