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/jobs/test_scheduler_job.py
state=State.FAILED,
            execution_date=DEFAULT_DATE + timedelta(days=1),
            start_date=DEFAULT_DATE + timedelta(days=1),
            session=session,
        )
        ti = dr.get_task_instance(task_id=op1.task_id, session=session)
        ti.state = initial_task_state
        session.commit()
        
        
        scheduler = SchedulerJob(num_runs=2, processor_poll_interval=30)
        scheduler.dagbag = dagbag
        executor = MockExecutor(do_update=False)
        executor.queued_tasks
        scheduler.executor = executor
        processor = mock.MagicMock()
        processor.done = False
        scheduler.processor_agent = processor
        with mock.patch.object(settings, "USE_JOB_SCHEDULE", False), conf_vars(
            {('scheduler', 'clean_tis_without_dagrun_interval'): '0.001'}
        ):
            scheduler._run_scheduler_loop()
        ti = dr.get_task_instance(task_id=op1.task_id, session=session)
        assert ti.state == expected_task_state
        assert ti.start_date is not None
        if expected_task_state in State.finished:
            assert ti.end_date is not None
            assert ti.start_date == ti.end_date
            assert ti.duration is not None
    def test_dagrun_timeout_verify_max_active_runs(self):