This only crashes on the release22-maint branch, and
only when coredump is true:

class UserLong(object):
    def __pow__(self, *args):
        pass

coredump = 1

if not coredump:
   int.__mro__

pow(0, UserLong(), 0)

It's the type of the first argument to pow() that's
relavent: if you change it to "pow(0L, UserLong(), 0)"
you then have to change "int.__mro__" to "long.__mro__"
to avoid the crash.

Maybe it was the "typeobject.c refactoring" patch that
accidentally fixed this on the trunk?