We have flaky scheduler test:


https://github.com/apache/airflow/pull/11659/checks?check_run_id=1279791496#step:6:527


_______________ TestSchedulerJob.test_scheduler_task_start_date ________________

self = <tests.jobs.test_scheduler_job.TestSchedulerJob testMethod=test_scheduler_task_start_date>

    def test_scheduler_task_start_date(self):
        """
        Test that the scheduler respects task start dates that are different from DAG start dates
        """
    
        dagbag = DagBag(dag_folder=os.path.join(settings.DAGS_FOLDER, "no_dags.py"), include_examples=False)
        dag_id = 'test_task_start_date_scheduling'
        dag = self.dagbag.get_dag(dag_id)
        dag.is_paused_upon_creation = False
        dagbag.bag_dag(dag=dag, root_dag=dag)
    
        # Deactivate other dags in this file so the scheduler doesn't waste time processing them
        other_dag = self.dagbag.get_dag('test_start_date_scheduling')
        other_dag.is_paused_upon_creation = True
        dagbag.bag_dag(dag=other_dag, root_dag=other_dag)
    
        dagbag.sync_to_db()
    
        scheduler = SchedulerJob(executor=self.null_exec,
                                 subdir=dag.fileloc,
                                 num_runs=2)
        scheduler.run()
    
        session = settings.Session()
        tiq = session.query(TaskInstance).filter(TaskInstance.dag_id == dag_id)
        ti1s = tiq.filter(TaskInstance.task_id == 'dummy1').all()
        ti2s = tiq.filter(TaskInstance.task_id == 'dummy2').all()
        self.assertEqual(len(ti1s), 0)
>       self.assertEqual(len(ti2s), 2)
E       AssertionError: 1 != 2
tests/models/test_taskinstance.py
for task_id, expected_state in ti_state_mapping.items():
            task_instance = dag_run.get_task_instance(task_id=task_id)
            assert task_instance.state == expected_state, error_message
    @parameterized.expand(
        [
            (
                {('scheduler', 'schedule_after_task_execution'): 'True'},
                {'A': 'B', 'B': 'C'},
                {'A': State.QUEUED, 'B': State.NONE, 'C': State.NONE},
                {'A': State.SUCCESS, 'B': State.SCHEDULED, 'C': State.NONE},
                {'A': State.SUCCESS, 'B': State.SUCCESS, 'C': State.SCHEDULED},
                "A -> B -> C, with fast-follow ON when A runs, B should be QUEUED. Same for B and C.",
            ),
            (
                {('scheduler', 'schedule_after_task_execution'): 'False'},
                {'A': 'B', 'B': 'C'},
                {'A': State.QUEUED, 'B': State.NONE, 'C': State.NONE},
                {'A': State.SUCCESS, 'B': State.NONE, 'C': State.NONE},
                None,
                "A -> B -> C, with fast-follow OFF, when A runs, B shouldn't be QUEUED.",
            ),
            (
                {('scheduler', 'schedule_after_task_execution'): 'True'},
                {'A': 'B', 'C': 'B', 'D': 'C'},
                {'A': State.QUEUED, 'B': State.NONE, 'C': State.NONE, 'D': State.NONE},