**Apache Airflow version: 2.0.1**
**What happened:**
Running an airflow dags test or backfill  CLI command shown in tutorial, produces the same error.

**dags test cli command result：**

```
(airflow_venv) (base) app@lunar_01:airflow$ airflow dags test tutorial 2015-06-01
[2021-02-16 04:29:22,355] {dagbag.py:448} INFO - Filling up the DagBag from /home/app/Lunar/src/airflow/dags
[2021-02-16 04:29:22,372] {example_kubernetes_executor_config.py:174} WARNING - Could not import DAGs in example_kubernetes_executor_config.py: No module named 'kubernetes'
[2021-02-16 04:29:22,373] {example_kubernetes_executor_config.py:175} WARNING - Install kubernetes dependencies with: pip install apache-airflow['cncf.kubernetes']
Traceback (most recent call last):
  File "/home/app/airflow_venv/bin/airflow", line 10, in <module>
    sys.exit(main())
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/__main__.py", line 40, in main
    args.func(args)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/cli/cli_parser.py", line 48, in command
    return func(*args, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/session.py", line 65, in wrapper
    return func(*args, session=session, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/cli.py", line 89, in wrapper
    return f(*args, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/cli/commands/dag_command.py", line 389, in dag_test
    dag.run(executor=DebugExecutor(), start_date=args.execution_date, end_date=args.execution_date)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/models/dag.py", line 1706, in run
    job.run()
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/jobs/base_job.py", line 237, in run
    self._execute()
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/session.py", line 65, in wrapper
    return func(*args, session=session, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/jobs/backfill_job.py", line 805, in _execute
    session=session,
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/session.py", line 62, in wrapper
    return func(*args, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/jobs/backfill_job.py", line 715, in _execute_for_run_dates
    tis_map = self._task_instances_for_dag_run(dag_run, session=session)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/session.py", line 62, in wrapper
    return func(*args, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/jobs/backfill_job.py", line 359, in _task_instances_for_dag_run
    dag_run.refresh_from_db()
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/session.py", line 65, in wrapper
    return func(*args, session=session, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/models/dagrun.py", line 178, in refresh_from_db
    DR.run_id == self.run_id,
  File "/home/app/airflow_venv/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3500, in one
    raise orm_exc.NoResultFound("No row was found for one()")
sqlalchemy.orm.exc.NoResultFound: No row was found for one()
```

**backfill cli command result:**
```
(airflow_venv) (base) app@lunar_01:airflow$ airflow dags backfill tutorial --start-date 2015-06-01 --end-date 2015-06-07
/home/app/airflow_venv/lib/python3.7/site-packages/airflow/cli/commands/dag_command.py:62 PendingDeprecationWarning: --ignore-first-depends-on-past is deprecated as the value is always set to True
[2021-02-16 04:30:16,979] {dagbag.py:448} INFO - Filling up the DagBag from /home/app/Lunar/src/airflow/dags
[2021-02-16 04:30:16,996] {example_kubernetes_executor_config.py:174} WARNING - Could not import DAGs in example_kubernetes_executor_config.py: No module named 'kubernetes'
[2021-02-16 04:30:16,996] {example_kubernetes_executor_config.py:175} WARNING - Install kubernetes dependencies with: pip install apache-airflow['cncf.kubernetes']
Traceback (most recent call last):
  File "/home/app/airflow_venv/bin/airflow", line 10, in <module>
    sys.exit(main())
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/__main__.py", line 40, in main
    args.func(args)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/cli/cli_parser.py", line 48, in command
    return func(*args, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/cli.py", line 89, in wrapper
    return f(*args, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/cli/commands/dag_command.py", line 116, in dag_backfill
    run_backwards=args.run_backwards,
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/models/dag.py", line 1706, in run
    job.run()
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/jobs/base_job.py", line 237, in run
    self._execute()
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/session.py", line 65, in wrapper
    return func(*args, session=session, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/jobs/backfill_job.py", line 805, in _execute
    session=session,
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/session.py", line 62, in wrapper
    return func(*args, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/jobs/backfill_job.py", line 715, in _execute_for_run_dates
    tis_map = self._task_instances_for_dag_run(dag_run, session=session)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/session.py", line 62, in wrapper
    return func(*args, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/jobs/backfill_job.py", line 359, in _task_instances_for_dag_run
    dag_run.refresh_from_db()
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/utils/session.py", line 65, in wrapper
    return func(*args, session=session, **kwargs)
  File "/home/app/airflow_venv/lib/python3.7/site-packages/airflow/models/dagrun.py", line 178, in refresh_from_db
    DR.run_id == self.run_id,
  File "/home/app/airflow_venv/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3500, in one
    raise orm_exc.NoResultFound("No row was found for one()")
sqlalchemy.orm.exc.NoResultFound: No row was found for one()
```
airflow/models/dagrun.py
The emitted data may contains outlier (e.g. when the first task was cleared, so
        the second task's start_date will be used), but we can get rid of the outliers
        on the stats side through the dashboards tooling built.
        Note, the stat will only be emitted if the DagRun is a scheduler triggered one
        (i.e. external_trigger is False).
        """
        if self.state == State.RUNNING:
            return
        if self.external_trigger:
            return
        if not finished_tis:
            return
        try:
            dag = self.get_dag()
            if not self.dag.schedule_interval or self.dag.schedule_interval == "@once":
                
                return
            ordered_tis_by_start_date = [ti for ti in finished_tis if ti.start_date]
            ordered_tis_by_start_date.sort(key=lambda ti: ti.start_date, reverse=False)
            first_start_date = ordered_tis_by_start_date[0].start_date
            if first_start_date:
                
                
                
                true_delay = first_start_date - dag.following_schedule(self.execution_date)
                if true_delay.total_seconds() > 0:
                    Stats.timing(f'dagrun.{dag.dag_id}.first_task_scheduling_delay', true_delay)
        except Exception as e:
            self.log.warning(f'Failed to record first_task_scheduling_delay metric:\n{e}')
    def _emit_duration_stats_for_finished_state(self):