title: Django: apps.get_models() yields models from unittests
body: <p>If I call this django method, in a test, it yields a lot of models which are not installed.<br>
  These models are from other apps test code.</p>
  
  <p>For example, when iI use <code>apps.get_models()</code> I get <code>MROBase1</code> from the django package polymorphic test code.</p>
  
  <p><strong>=></strong> I want get all models which have a table in the database. In above question I got a model which exists just for testing, which is not on the database.</p>
  
  <p><strong>NB:</strong> I use Django 1.10</p>