the test set as it only tested with a zip archive in the current directory,
but it doesn't work at all for packages when the zip archive was specified
as an absolute path. It's a real embarrassing bug: a strchr call should
have been strrchr; fever apparently implies dyslexia.

Second stupid bug: the zipimport test failed with a name error
__importer__ (which I had renamed to __loader__ everywhere but here).
I would've sworn I ran the test after that change but that can't be true.
What I don't understand that noone reported a failing test_zipimport.py
before the release of 2.3a1.