title: Return false and rollback in after_save callback
body: <p>In ActiveRecord model after_save callback I need to ROLLBACK transaction and return false.</p>
  
  <pre><code>def after_save_callback
    if mycondition?
      raise ActiveRecord::Rollback
    end
  end
  </code></pre>
  
  <p>This callback rolls-back transaction but mymodel.save! returns true. How to make it return false and rollback?</p>