title: Django migrations - how to make it forget?
body: <p>I've been sketching out a new Django app with the runserver dev server running in a background window to tracking network wiring, and <em>briefly</em> had this in my model:</p>
  
  <pre><code>class Interface(models.Model):
      name = models.CharField(max_length=200)
      # (blah)
  
  class Connection(models.Model):
      interface_from = models.ForeignKey(Interface, related_name="connections")
      interface_to = models.ForeignKey(Interface, related_name="connections")
      source = models.CharField(max_length=32)
  </code></pre>
  
  <p>Before I realised I couldn't have the same related_name for two fields. I guess I will need to write something special to find all connections related to an interface, since they might be the 'to' or 'from' end of the connection (be interested in any insight on a nicer way to do that - like a "Set" field)</p>
  
  <p>At this point, I hadn't done a makemigrations, but on stopping the server, and making my migrations, I get:</p>
  
  <pre><code>ERRORS:
  autodoc.Connection.interface_from: (fields.E304) Reverse accessor for 'Connection.interface_from' clashes with reverse accessor for 'Connection.interface_to'.
  HINT: Add or change a related_name argument to the definition for 'Connection.interface_from' or 'Connection.interface_to'.
  </code></pre>
  
  <p>Even though there isn't a clash anymore. I don't see a migrations directory anywhere - this was the initial pass at the models - so where is the memory of this error coming from after a restart of the dev server?</p>
  
  <p>Edit: To make it clearer, my Connection model now looks like:</p>
  
  <pre><code>class Connection(models.Model):
      interface_from = models.ForeignKey(Interface)
      interface_to = models.ForeignKey(Interface)
      source = models.CharField(max_length=32)
  </code></pre>