Log Message:
py-test: updated to 4.0.1

pytest 4.0.1:

Bug Fixes
- Display warnings before "short test summary info" again, but still \ 
later warnings in the end.
- Handle uninitialized exceptioninfo in repr/str.
- Do not create .gitignore/README.md files in existing cache directories.
- Rearrange warning handling for the yield test errors so the opt-out in 4.0.x \ 
correctly works.
- Fix collection of testpaths with --pyargs.
- Fix assertion rewriting involving Starred + side-effects.
- Ensure we resolve the absolute path when the given --basetemp is a relative path.

- Use pkg_resources.parse_version instead of LooseVersion in minversion check.
- Adjust the stack level of some internal pytest warnings.