title: Django cascade delete and post_delete signal
body: <p>In my application <code>post_delete</code> signals being recorded in a specific model and when it was removed.</p>
  
  <pre><code>class A(models.Model):
      ...
  
  class B(models.Model):
      a = models.ForeignKey('A')
  
  class C(models.Model):
      b = models.ForeignKey('B')
  
  def log_delete(sender, instance, **kwargs):
      logging
  
  post_delete.connect(log_delete, sender = A)
  post_delete.connect(log_delete, sender = C)
  </code></pre>
  
  <p>When you delete an instance of A cascade delete occurs removing B and C instances. How can I disable signal for child instances on cascade delete by django?</p>