docs: def save_model(self, request, obj, form, change):
          """
          Provides a warning if the user is an active admin with no admin access.
          """
          super(SitePermissionUserAdmin, self).save_model(
              request, obj, form, change)
          user = self.model.objects.get(id=obj.id)
          has_perms = len(user.get_all_permissions()) > 0
          has_sites = SitePermission.objects.filter(user=user).count() > 0
          if user.is_active and user.is_staff and not user.is_superuser and not (
                  has_perms and has_sites):
              error(request, "The user is active but won't be able to access "
                             "the admin, due to no edit/site permissions being "
                             "selected")