Message 149286 - Python tracker

Ok, a couple of further (minor) issues:
- I don't think AssertionError is the right exception type. TypeError should be used when a type mismatches (e.g. "not an unicode object");
- you don't need to check for d_type being NULL, since other methods don't;
- if type_qualname == NULL, the original error should be retained.

Otherwise, looks good, thank you.