C basetype problem, works on 2.3, not on 2.2.1

[Todd Miller]

This problem turned out to be a result of two things:

1. Python-2.3 and Python-2.2.1 treatments of mapping method setup in a 
class instance are not identical.  They do, however, have the same 
functional behavior, with 2.3 also having improved performance.

2. My new basetype was defining both sequence and mapping protocols, and
the sequence protocol was given precedence.  By dropping the sequence 
protocol and only defining the mapping protocol, my problem went away 
for Python-2.2.1.

Thanks Guido!

Todd