Singleton scope leaks instances from child injectors about injector HOT 2 CLOSED

class TestChildScope(unittest.TestCase):
    def test_child_scope(self):
        TestKey = Key('test')
        TestKey2 = Key('test2')

        def parent_module(binder):
            binder.bind(TestKey, to=object, scope=singleton)

        def first_child_module(binder):
            binder.bind_scope(SingletonScope)
            binder.bind(TestKey2, to=object, scope=singleton)

        def second_child_module(binder):
            binder.bind_scope(SingletonScope)
            binder.bind(TestKey2, to='marker', scope=singleton)

        injector = Injector(modules=[parent_module])
        first_child_injector = injector.create_child_injector(modules=[first_child_module])
        second_child_injector = injector.create_child_injector(modules=[second_child_module])

        self.assertIsNot(first_child_injector.get(TestKey2), second_child_injector.get(TestKey2))
        self.assertIs(first_child_injector.get(TestKey), second_child_injector.get(TestKey))