title: Celery celery_taskmeta table for results backend not saving until task completed
body: <p>My celery is using postgresql for a backend, but it seems that the celery_taskmeta table is only created and tasks saved to it only after they're completed, rather than being able to track which ones are in the various status states.</p>
  
  <p>Is there some configuration issue for me that would cause that? Or does it only save the final result to the backend, rather than the status along the way.</p>