We do not use option groups, so drop related code

accounts/forms.py

@@ -73,22 +73,11 @@ class SortedSelectMixin(object):
 
         # Stolen from Select.render_options
         for option_value, option_label in all_choices:
-            if isinstance(option_label, (list, tuple)):
-                output.append(
-                    u'<optgroup label="%s">' %
-                    escape(force_unicode(option_value))
-                )
-                for option in option_label:
-                    output.append(
-                        self.render_option(selected_choices, *option)
-                    )
-                output.append(u'</optgroup>')
-            else:
-                output.append(
-                    self.render_option(
-                        selected_choices, option_value, option_label
-                    )
+            output.append(
+                self.render_option(
+                    selected_choices, option_value, option_label
                 )
+            )
         return u'\n'.join(output)