`py.test -p project.lock8.plugin /tmp project --custom-option` fails with > py.test: error: unrecognized arguments: --custom-option The option is defined through `pytest_addoption` and `parser.addoption` therein. Using an additional directory outside of $PWD seems to cause this. I have tried using `--confcutdir=$PWD`, but it still did not work. pytest 2.9.3.dev0 (current master).