Message2896

Looks good to me too, so I applied the updated version to trunk in r3506.

I did make a couple of tiny changes.  The unicode___mod__ method needed to be package protected and final.  Those type methods are always final as they're used to implement the type specific method implementation used by the descriptor, and it shouldn't be overrideable by a subclass.  That also means the whole implementation of the method needs to be in unicode___mod__ so the descriptor gets the full behavior, and the PyObject method for that function, __mod__ in this case, should just call the type specific method and that's it.