I read a few of the logs, and all errors roots in the same place, when the test case tries to remove the tempdir during teardown/cleanup. The Windows (and other platforms not supporting directory fds) implementation of rmtree can have race conditions if files are added while the directory being walked, causing the error.

I don’t know the case of CPython, but Pipenv has a similar problem when running concurrent tests with subprocesses. We never solved it (but simply wrap the rmtree call inside a try block and look away).