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
task = DummyOperator(task_id='op')
        ti = TI(task=task, execution_date=datetime.datetime.now())
        params = {"override": False}
        dag_run = DagRun()
        ti.overwrite_params_with_dag_run_conf(params, dag_run)
        assert params["override"] is False
    @patch('airflow.models.taskinstance.send_email')
    def test_email_alert(self, mock_send_email):
        dag = models.DAG(dag_id='test_failure_email')
        task = BashOperator(
            task_id='test_email_alert', dag=dag, bash_command='exit 1', start_date=DEFAULT_DATE, email='to'
        )
        ti = TI(task=task, execution_date=timezone.utcnow())
        try:
            ti.run()
        except AirflowException:
            pass
        (email, title, body), _ = mock_send_email.call_args
        assert email == 'to'
        assert 'test_email_alert' in title
        assert 'test_email_alert' in body
        assert 'Try 1' in body
    @conf_vars(
        {
            ('email', 'subject_template'): '/subject/path',
            ('email', 'html_content_template'): '/html_content/path',
        }
    )
    @patch('airflow.models.taskinstance.send_email')
    def test_email_alert_with_config(self, mock_send_email):