> I'm currently leaning towards having sys.path_importer_cache store 
> the actual directory name.

Exactly what I meant by "Creating a new entry in sys.path_importer_cache after changing directories and importing a new module", but expressed much more succinctly :)  Good to see we're on pretty much the same page.


Here's a (very) preliminary patch for the issue that stores the directory name as a key in sys.path_importer_cache and ensures module.__file__ is an absolute path. 

I've also modified test_path_importer_cache_empty_string in test_importlib/import_/test_path.py to use os.getcwd() instead of os.curdir as the key for sys.path_importer_cache.

Finally, I've added a test to test_import.py that tests that module.__file__ is equivalent to os.path.abspath(module.__file__).

Look it over when you get a chance and let me know what you would change.  Thanks...