Andi@Horzube MINGW64 ~/tmp
$ python3.7 ../pyTest.py
['', 'C:/ghc/msys64/mingw64/lib/python37.zip', 'C:/ghc/msys64/home/Andi/tmp', 'C:/ghc/msys64/mingw64/lib/python3.7', 'C:/ghc/msys64/mingw64/bin', 'C:/ghc/msys64/mingw64/lib/python3.7/lib-dynload', 'C:/ghc/msys64/mingw64/lib/python3.7/site-packages']

Andi@Horzube MINGW64 ~/tmp
$ python3.6 ../pyTest.py
['/home/Andi', '/usr/lib/python36.zip', '/usr/lib/python3.6', '/usr/lib/python3.6/lib-dynload', '/usr/lib/python3.6/site-packages']

Ignore the path prefix differences, they comes from slight differences how I installed these two versions.

3.6 lists '/home/Andi', path of the script
3.7 lists /home/Andi/tmp , path of cwd

This breaks existing code looking for files (imports primarily) relative to a scripts path.
If a file is placed in the right relative path to cwd it will be picked up over the intended file.

This should be at least mentioned in breaking changes.