Message 110084 - Python tracker

Some comments on the patch:
- shouldn't getdir_id use os.path.normcase() rather than manually switch on `windows`?
- the patch adds lots of names at the top-level which aren't part of the public API ("windows", "getdir_id", "defpath", "defpath_ext"). They should probably start with an underscore.
- if PATH is updated after shutil is first imported, the changes won't get picked up. Is it desired?