[Python-Dev] UserDict in 2.7

[Raymond Hettinger]

On Jun 22, 2010, at 10:08 AM, Benjamin Peterson wrote:
> . There was a typo in
> abc.py which prevented it from raising errors when non new-style class
> objects were passed in.

For 2.x, that was probably a good thing, a happy accident
that made it possible to register existing mapping classes
as a MutableMapping.

"Fixing" that typo will break code that currently uses ABCs
with old-style classes.  

I believe we are better-off leaving this as it was released in 2.6.


Raymond