Issue on Windows with uppercase folders with versions >= 5.1.0 and conftest

[jfthuong]

Hi,

Related to issue #2761, I have an issue in Windows with folders containing uppercase and conftest.py.

I have the following organization

E:/Prototypes/Toto/
  -> __init__.py
  -> conftest.py
  -> tests/
       -> test.py

See following files in zip: Toto.zip

When running pytest 5.1.2 (Python 3.7.1), I have the following error:

ImportError while loading conftest 'e:\prototypes\toto\conftest.py'.
ModuleNotFoundError: No module named 'toto'

This works fine with pytest 5.0.1:

platform win32 -- Python 3.7.1, pytest-5.0.1, py-1.8.0, pluggy-0.13.0
rootdir: E:\Prototypes\Toto
plugins: cov-2.6.1, forked-1.0.2, html-1.22.0, instafail-0.4.1, metadata-1.8.0, xdist-1.26.1
collected 2 items

tests\test_case.py .F

This is my list of installed modules:
pip_list.txt

[asottile]

I believe this is a duplciate of #5819