title: How can I exclude a declared field in ModelForm in form's subclass?
body: <p>In Django, I am trying to derive (subclass) a new form from <code>ModelForm</code> form where I would like to remove some fields (or to have only some fields, to be more correct). Of course obvious way would be to do (base form is from <code>django.contrib.auth.forms</code>):</p>
  
  <pre><code>class MyUserChangeForm(UserChangeForm):
    class Meta(UserChangeForm.Meta):
      fields = ('first_name', 'last_name', 'email')
  </code></pre>
  
  <p>But this does not work as it adds/keeps also an <code>username</code> field in the resulting form. This field was declared explicitly in <code>UserChangeForm</code>. Even adding <code>username</code> to <code>exclude</code> attribute does not help.</p>
  
  <p>Is there some proper way to exclude it and I am missing something? Is this a bug? Is there some workaround?</p>