methods of data-less C mix-in classes, C-based __call_method__
        hooks were broken.  The most notable example of this was the
        breaking of the Synchronized class.

      - Calling C-base-class special methods from overriding methods,
        as in::

          class LowerMultiMapping(MultiMapping):

	    def __getitem__(self, key):
	      return MultiMapping.__getitem__(self, lower(key))

        caused infinite loops.

Added new copyright.