title: Trigering post_save signal only after transaction has completed
body: <p>I have written some APIs, for which the respective functions executive inside a transaction block. I am calling the <code>save()</code> method (after some modifications) on instance/s of a/several Model/s, and also consecutively indexing some JSON related information of the instance/s in <strong>Elasticsearch</strong>. I want the database to rollback even if for some reason the <code>save()</code> for one of the instances or indexing to the <strong>Elasticsearch</strong> fails. </p>
  
  <p>Now, the problem is arising that even inside the transaction block, the <code>post_save()</code> signals gets called, and that is an issue because some notifications are being triggered from those signals.</p>
  
  <p>Is there a way to trigger <code>post_save()</code> signals only after the transactions have completed successful?</p>