**Apache Airflow version**: 2.0.0b3

**Environment**: Python3.7-slim running on docker

**What happened**:

Error when running `airflow tasks test <dag> <task> <date>` there is an error with the task rescheduler, which should not happen as we are testing the tasks and not running via scheduler. 

**What you expected to happen**:

No error message should be displayed as the task is success and it is running on test mode

**How to reproduce it**:

just run the `airflow test <dag> <task> <date>` after a vanilla airflow installation using pip install.

**Anything else we need to know**:
this is the log
```
root@add8b3f038cf:/# airflow  tasks test docker_test d 2020-11-24 
[2020-11-24 08:13:00,796] {dagbag.py:440} INFO - Filling up the DagBag from /opt/airflow/dags/test
[2020-11-24 08:13:01,072] {taskinstance.py:827} INFO - Dependencies all met for <TaskInstance: docker_test.d 2020-11-24T00:00:00+00:00 [None]>
[2020-11-24 08:13:01,077] {taskinstance.py:827} INFO - Dependencies all met for <TaskInstance: docker_test.d 2020-11-24T00:00:00+00:00 [None]>
[2020-11-24 08:13:01,077] {taskinstance.py:1018} INFO - 
--------------------------------------------------------------------------------
[2020-11-24 08:13:01,077] {taskinstance.py:1019} INFO - Starting attempt 1 of 4
[2020-11-24 08:13:01,077] {taskinstance.py:1020} INFO - 
--------------------------------------------------------------------------------
[2020-11-24 08:13:01,078] {taskinstance.py:1039} INFO - Executing <Task(PythonOperator): d> on 2020-11-24T00:00:00+00:00
[2020-11-24 08:13:01,109] {taskinstance.py:1232} INFO - Exporting the following env vars:
AIRFLOW_CTX_DAG_EMAIL=adilson@zookal.com
AIRFLOW_CTX_DAG_OWNER=airflow
AIRFLOW_CTX_DAG_ID=docker_test
AIRFLOW_CTX_TASK_ID=d
AIRFLOW_CTX_EXECUTION_DATE=2020-11-24T00:00:00+00:00
d
[2020-11-24 08:13:01,110] {python.py:118} INFO - Done. Returned value was: None
[2020-11-24 08:13:01,115] {taskinstance.py:1143} INFO - Marking task as SUCCESS. dag_id=docker_test, task_id=d, execution_date=20201124T000000, start_date=20201124T081301, end_date=20201124T081301
Traceback (most recent call last):
  File "/usr/local/bin/airflow", line 8, in <module>
    sys.exit(main())
  File "/usr/local/lib/python3.7/site-packages/airflow/__main__.py", line 40, in main
    args.func(args)
  File "/usr/local/lib/python3.7/site-packages/airflow/cli/cli_parser.py", line 50, in command
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/airflow/utils/cli.py", line 86, in wrapper
    return f(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/airflow/cli/commands/task_command.py", line 379, in task_test
    ti.run(ignore_task_deps=True, ignore_ti_state=True, test_mode=True)
  File "/usr/local/lib/python3.7/site-packages/airflow/utils/session.py", line 63, in wrapper
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/airflow/models/taskinstance.py", line 1350, in run
    mark_success=mark_success, test_mode=test_mode, job_id=job_id, pool=pool, session=session
  File "/usr/local/lib/python3.7/site-packages/airflow/utils/session.py", line 59, in wrapper
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/airflow/models/taskinstance.py", line 1152, in _run_raw_task
    self._run_mini_scheduler_on_child_tasks(session)
  File "/usr/local/lib/python3.7/site-packages/airflow/utils/session.py", line 59, in wrapper
    return func(*args, **kwargs)
  File "/usr/local/lib/python3.7/site-packages/airflow/models/taskinstance.py", line 1165, in _run_mini_scheduler_on_child_tasks
    execution_date=self.execution_date,
  File "/usr/local/lib/python3.7/site-packages/sqlalchemy/orm/query.py", line 3473, in one
    raise orm_exc.NoResultFound("No row was found for one()")
sqlalchemy.orm.exc.NoResultFound: No row was found for one()
```


airflow/models/taskinstance.py
#
#
#
import contextlib
import getpass
import hashlib
import logging
import math
import os
import signal
import time
import warnings
from datetime import datetime, timedelta
from typing import Any, Dict, Iterable, List, NamedTuple, Optional, Tuple, Union
from urllib.parse import quote
import dill
import jinja2
import lazy_object_proxy
import pendulum
from jinja2 import TemplateAssertionError, UndefinedError
from sqlalchemy import Column, Float, Index, Integer, PickleType, String, and_, func, or_
from sqlalchemy.exc import OperationalError
from sqlalchemy.orm import reconstructor, relationship
from sqlalchemy.orm.session import Session
from sqlalchemy.sql.elements import BooleanClauseList