Class longclone

Lib/test/test_descr.py:2920–2921

        # Because octlong overrides __add__, we can't check the absence of +0
        # optimizations using octlong.
        class longclone(int):
            pass
        a = longclone(1)
        self.assertIs((a + 0).__class__, int)
        self.assertIs((0 + a).__class__, int)