title: Customizing an Admin form in Django while also using autodiscover
body: <p>I want to modify a few tiny details of Django's built-in <code>django.contrib.auth</code> module.  Specifically, I want a different form that makes username an email field (and email an alternate email address.   (I'd rather not modify <code>auth</code> any more than necessary -- a simple form change <em>seems</em> to be all that's needed.)</p>
  
  <p>When I use <code>autodiscover</code> with a customized <code>ModelAdmin</code> for <code>auth</code> I wind up conflicting with <code>auth</code>'s own admin interface and get an "already registered" error.</p>
  
  <p>It looks like I have to create my own admin site, enumerating all of my Models.  It's only 18 classes, but it seems like a DRY problem -- every change requires both adding to the Model <strong>and</strong> adding to the customized admin site.</p>
  
  <p>Or, should I write my own version of "<code>autodiscover</code> with exclusions" to essentially import all the <code>admin</code> modules <strong>except</strong> <code>auth</code>?</p>