This tests fails occasionally on mysql at least:

https://github.com/apache/airflow/pull/11555/checks?check_run_id=1260840314#step:9:1125

```
=================================== FAILURES ===================================
_____________ TestSchedulerJob.test_no_orphan_process_will_be_left _____________

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

    def test_no_orphan_process_will_be_left(self):
        empty_dir = mkdtemp()
        current_process = psutil.Process()
        old_children = current_process.children(recursive=True)
        scheduler = SchedulerJob(subdir=empty_dir,
                                 num_runs=1,
                                 executor=MockExecutor(do_update=False))
        scheduler.run()
        shutil.rmtree(empty_dir)
    
        # Remove potential noise created by previous tests.
        current_children = set(current_process.children(recursive=True)) - set(
            old_children)
>       self.assertFalse(current_children)
E       AssertionError: {psutil.Process(pid=3474, name='/usr/local/bin/', status='running', started='19:26:22')} is not false

tests/jobs/test_scheduler_job.py:871: AssertionError
```



tests/models/test_taskinstance.py
session = settings.Session()
        dag = models.DAG(dag_id='test_get_num_running_task_instances')
        dag2 = models.DAG(dag_id='test_get_num_running_task_instances_dummy')
        task = DummyOperator(task_id='task', dag=dag, start_date=DEFAULT_DATE)
        task2 = DummyOperator(task_id='task', dag=dag2, start_date=DEFAULT_DATE)
        ti1 = TI(task=task, execution_date=DEFAULT_DATE)
        ti2 = TI(task=task, execution_date=DEFAULT_DATE + datetime.timedelta(days=1))
        ti3 = TI(task=task2, execution_date=DEFAULT_DATE)
        ti1.state = State.RUNNING
        ti2.state = State.QUEUED
        ti3.state = State.RUNNING
        session.add(ti1)
        session.add(ti2)
        session.add(ti3)
        session.commit()
        assert 1 == ti1.get_num_running_task_instances(session=session)
        assert 1 == ti2.get_num_running_task_instances(session=session)
        assert 1 == ti3.get_num_running_task_instances(session=session)
    
    
    
    
    
    
    
    
    
    
    
    def test_log_url(self):