handle sites without a national registration number field

src/authentic2_auth_fedict/signals.py

@@ -24,13 +24,14 @@ def on_user_logged_in(sender, request, user, **kwargs):
         return
     if user.backend == 'authentic2_auth_fedict.backends.FedictBackend':
         return
+    attribute = None
     for attr_name in ('niss', 'nrn'):
         try:
             attribute = Attribute.objects.get(name=attr_name)
+            break
         except Attribute.DoesNotExist:
             pass
-        break
-    else:
+    if not attribute:
         return
     try:
         av = AttributeValue.objects.with_owner(user).filter(attribute=attribute, verified=True)[0]