def test_withUnsetOnRaise(self):
        action = Action(MemoryLogger(), "", TaskLevel(level=[]), "")
        try:
            with action:
                1/0
        except ZeroDivisionError:
            pass
        else:
            self.fail("no exception")
        self.assertIs(currentAction(), None)
L{Action.__exit__} unsets the action if the block raises an exception.
dataset/ETHPy150Open ClusterHQ/eliot/eliot/tests/test_action.py/ActionTests.test_withUnsetOnRaise