title: Clear Failed Airflow DAG But Don't Restart
body: <p>I'm running a custom backfill script that backfills a DAG serially. (If I run the backfill concurrently, I either run into a deadlock problem or a Serializable isolation problem.) As part of the process, I sometimes have failed DAGs mixed in with non-existing dates.  To backfill that failed date, I need to clear it first. The problem comes in that a cleared DAG auto restarts and conflicts with the first date running in the backfill.</p>
  <p><code>airflow clear dag_id -f -s 01-01-20 -e 01-12-20 -f</code></p>
  <p>Because of the way it is built, I'll have to rewrite it from scratch and clear each backfill individually. If I can prevent a cleared DAG from rerunning, I would save me some time. Is there a way to do this in the <code>cli</code>?</p>