title: Override Wagtail Admin login with AllAuth
body: <p>I am trying to override the Django Wagtail admin login with my AllAuth Login page.</p>
  
  <p>I've tried adding the following line from the Documentation to my settings.py</p>
  
  <blockquote>
    <p>WAGTAIL_FRONTEND_LOGIN_URL = '/accounts/login/'
    WAGTAILADMIN_USER_LOGIN_FORM = 'admin.site.login'</p>
  </blockquote>
  
  <p>But I receive this error when I try to visit /admin url that renders the wagtail admin login view. </p>
  
  <pre><code>Exception Type: ImproperlyConfigured
  Exception Value:    
  WAGTAILADMIN_USER_LOGIN_FORM refers to a form 'admin.site.login' that is not available
  </code></pre>