[views/retriever] fix signature

views.py

@@ -57,7 +57,7 @@ class XRemoteUserRetriever(authentication.WebAuthInfoRetreiver):
             return False
         return True
 
-    def revalidate_login(self):
+    def revalidate_login(self, req):
         try:
             login, realm = req.get_header('x-remote-user', None).split('@')
         except Exception: