title: how to operate in airflow so that the task rerun and continue downstream tasks
body: <p>I set up a work flow in airflow, one of jobs was failed, after I fixed the problem, I want to rerun the failed task and continue the workflow.the details like below:</p>
  
  <p><a href="https://i.stack.imgur.com/3RWxk.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3RWxk.jpg" alt="enter image description here"></a></p>
  
  <p>as above, I prepared to run the task "20_validation", I pressed the button 'Run' like below:</p>
  
  <p><a href="https://i.stack.imgur.com/3iM2P.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/3iM2P.jpg" alt="enter image description here"></a></p>
  
  <p>but the problem is when the task '20_validation' has finished, these downstream tasks were not continue to be started. How should I do?</p>