Unable to pass a file through custom cli option

[MarcinKonowalczyk]

to reproduce (with uv, but basically just from a fresh venv):

mkdir temp && cd temp
uv venv && .venv/bin/activate
pip install pytest
cat <<EOF > conftest.py
import pytest
def pytest_addoption(parser):
    parser.addoption(
        "--ruby",
        action="store",
        help="specify the ruby executable to use for tests",
    )
def pytest_configure(config):
    config.addinivalue_line("markers", "ruby: specify the ruby executable to use for tests")

@pytest.fixture(scope="session")
def ruby(request):
    return request.config.getoption("--ruby", None)
EOF
cat <<EOF | test_me.py
def test_me(ruby):
    print("Ruby: ", ruby)
EOF

and then

pytest --ruby '/usr/bin/not-ruby' # works ok and prints the path in test
pytest --ruby '/usr/bin/ruby' # fails

the error is:

ERROR: usage: pytest [options] [file_or_dir] [file_or_dir] [...]
pytest: error: unrecognized arguments: --ruby
  inifile: None
  rootdir: /usr/bin

looks like the parser is picking up the path as part of the root dir, but only if it exists...?

pip list output:

Package   Version
--------- -------
iniconfig 2.1.0
packaging 24.2
pluggy    1.5.0
pytest    8.3.5