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
count = scheduler._schedule_dag_run(dr, set(), session)
            assert count == 1
            session.refresh(ti)
            assert ti.state == State.SCHEDULED
    @parameterized.expand(
        [
            [State.NONE, None, None],
            [
                State.UP_FOR_RETRY,
                timezone.utcnow() - datetime.timedelta(minutes=30),
                timezone.utcnow() - datetime.timedelta(minutes=15),
            ],
            [
                State.UP_FOR_RESCHEDULE,
                timezone.utcnow() - datetime.timedelta(minutes=30),
                timezone.utcnow() - datetime.timedelta(minutes=15),
            ],
        ]
    )
    def test_dag_file_processor_process_task_instances_depends_on_past(self, state, start_date, end_date):
        """
        Test if _process_task_instances puts the right task instances into the
        mock_list.
        """
        dag = DAG(
            dag_id='test_scheduler_process_execute_task_depends_on_past',
            start_date=DEFAULT_DATE,
            default_args={
                'depends_on_past': True,
            },