Ensure that this works:

```python
@setup
def mytask():
    print("I am a setup task")

with dag_maker() as dag:
    mytask.override(task_id='newtask')

assert len(dag.task_group.children) == 1
setup_task = dag.task_group.children["newtask"]
assert setup_task._is_setup
```
and teardown also works
pass
        class DummyTask(BaseOperator):
            deps = frozenset(list(BaseOperator.deps) + [DummyTriggerRule()])
        execution_date = datetime(2020, 1, 1)
        with DAG(dag_id="test_error_on_unregistered_ti_dep_serialization", start_date=execution_date) as dag:
            DummyTask(task_id="task1")
        with pytest.raises(SerializationError):
            SerializedBaseOperator.serialize_operator(dag.task_dict["task1"])
    def test_error_on_unregistered_ti_dep_deserialization(self):
        from airflow.operators.empty import EmptyOperator
        with DAG("test_error_on_unregistered_ti_dep_deserialization", start_date=datetime(2019, 8, 1)) as dag:
            EmptyOperator(task_id="task1")
        serialize_op = SerializedBaseOperator.serialize_operator(dag.task_dict["task1"])
        serialize_op["deps"] = [
            "airflow.ti_deps.deps.not_in_retry_period_dep.NotInRetryPeriodDep",
            
            "test_plugin.NotATriggerRule",
        ]
        with pytest.raises(SerializationError):
            SerializedBaseOperator.deserialize_operator(serialize_op)
    def test_serialize_and_deserialize_custom_ti_deps(self):
        from test_plugin import CustomTestTriggerRule
        class DummyTask(BaseOperator):