Probably both those conditions can't be satisfied;  I'm wasn't sure what happened if something's __index__ method returned something other than an int or long.

But now I bother to look at the source (in Objects/abstract.c) I see that there *is* already an explicit check for the result of nb_index being int or long (with TypeError being raised if the result isn't one of those).  Mea culpa.  I'll remove those lines (though I may leave an assert, just to be on the safe side).

The 2.x behaviour isn't ideal:  I'd prefer to just stop if the __index__ method is present and raises TypeError, rather than going on to check __int__ in that case.  But that presents problems with old-style classes, where PyIndex_Check is true even when no __index__ method is explicitly defined.

Thanks for the extra tests!