Earlier quoted context omitted.
Maybe have a proxy https://pypi.python.org/pypi/pyfilesystem that has `fs` as a requirement? That way even if people install with `pip install pyfilesystem`, you're good.
Hmm. That's an idea. Feels like a hack though. Do you know if there is a precedence for that?
If you run pip install py.test it fails with a message that you should run pip install pytest.