omg I found it

The single-process sequential case accidentally finds the `qwer` module because it happens to be in Astroid's cache after the linter checked `qwer` itself.

gitlab.com/pycqa/astroid/-/blo…

So it is *not* getting this error that is the bug, and the check is being called incorrectly. If it is to find modules, we need to put the top directory explicitly on `sys.path`.