I re-checked testzip-patch3.diff since some time has passed since I last commented on it, and it still seems to work ok (the small test_zipfile.py block failed to apply, but that's easy enough to do manually).  Passes full test run, test_zipfile64.py, etc., on Linux x86_64.

If there is something about the patch that still needs to be addressed before it can be committed, let me know and I'll see what I can do.