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
def fail():
            raise AirflowException("maybe this will pass?")
        dag = models.DAG(dag_id='test_retries_on_other_exceptions')
        task = PythonOperator(
            task_id='test_raise_other_exception',
            dag=dag,
            python_callable=fail,
            owner='airflow',
            start_date=timezone.datetime(2016, 2, 1, 0, 0, 0),
            retries=1,
        )
        ti = TI(task=task, execution_date=timezone.utcnow())
        try:
            ti.run()
        except AirflowException:
            pass  
        assert State.UP_FOR_RETRY == ti.state
    def _env_var_check_callback(self):