The leak seems to be due to the nested definitions of the Exception types A and B. It goes away if I move them out of the function so that it's like:


class A(Exception):
    pass
class B(Exception):
    pass

def test_no_hang_on_context_chain_cycle2():
    try:
        try:
            raise A()
        except A as _a:
            a = _a
            try:
                raise B()
            except B as _b:
                b = _b
        raise b
    except B:
        pass