title: Issue with ManyToMany Relationships not updating immediately after save
body: <p>I'm having issues with ManytoMany Relationships that are not updating
  in a model when I save it (via the admin) and try to use the new value within a
  function attached to the <code>post_save</code> signal or within the <code>save_model</code> of
  the associated <code>AdminModel</code>.
  I've tried to reload the object within those functions by using the
  get function with the id.. but it still has the old values.</p>
  
  <p>Is this a transaction issue? Is there a signal thrown when the
  transaction ends?</p>
  
  <p>Thanks,</p>