The parallel runner only forwarded pytest args after a literal '--', so a
bare 'scripts/run_tests.sh tests/foo.py -q' (or -v/-x/-k/--tb=long) errored
out with 'unrecognized arguments'. This contradicted the docstring's
promise that common pytest flags pass through, and forced a retry on every
run that used pytest muscle-memory.
Now any token starting with '-' that isn't one of the runner's own options
(-j/--jobs, --paths, --slice, --file-timeout, --generate-slices, --files,
--include-integration) is routed to each per-file pytest invocation
automatically. Value-taking flags given space-separated (-k expr, -m mark,
-p plugin, -o name=val, etc.) keep their value instead of having it stolen
by positional-path discovery. The explicit '--' separator still works and
stacks with bare flags.
- scripts/run_tests_parallel.py: argv splitter routes bare unknown flags to
pytest; value-flag lookahead; updated docstring.
- scripts/run_tests.sh: usage comment reflects bare-flag passthrough.
- tests/test_run_tests_parallel.py: 4 behavior-contract tests (bare -q runs,
-k keeps its value/filters, '--' still works, positional path stays a root).