I think the patch isn't entirely correct.  It uses PyIter_Check for detecting the case when an *iterable* raises TypeError, but that function actually checks for an *iterator*.  The check on the tp_iter member mentioned by Amaury Forgeot d'Arc probably would be better, but even that wouldn't detect every iterable: "Its presence normally signals that the instances of this type are iterable (although sequences may be iterable without this function)." (http://docs.python.org/dev/py3k/c-api/typeobj.html#PyTypeObject.tp_iter)  (Apparently any object with a __getitem__ is iterable.  By the way, collections.abc.Iterable also doesn't detect this case.)