add support for nrn attribute being named "niss"

src/authentic2_auth_fedict/signals.py

@@ -24,7 +24,14 @@ def on_user_logged_in(sender, request, user, **kwargs):
         return
     if user.backend == 'authentic2_auth_fedict.backends.FedictBackend':
         return
-    attribute = Attribute.objects.get(name='nrn')
+    for attr_name in ('niss', 'nrn'):
+        try:
+            attribute = Attribute.objects.get(name=attr_name)
+        except Attribute.DoesNotExist:
+            pass
+        break
+    else:
+        return
     try:
         av = AttributeValue.objects.with_owner(user).filter(attribute=attribute, verified=True)[0]
     except IndexError: