Parfois, l'username vaut none, et .lower ne marche pas.

cas_login.py

@@ -41,12 +41,13 @@ class CransCASBackend(CASBackend):
         utilisateur django s'il n'existe pas encore."""
 
         username, attributes = _verify(ticket, service)
+        # Si _verify plante, username contient None.
+        if username is None or not username:
+            return None
         # Sanitize username
         username = username.lower()
         if attributes:
             request.session['attributes'] = attributes
-        if not username:
-            return None
         try:
             user = User.objects.get(username=username)
         except User.DoesNotExist: