--- keystone/identity/backends/ldap/core.py.orig	2013-06-04 14:48:51.000000000 +0200
+++ keystone/identity/backends/ldap/core.py	2013-06-04 14:49:41.000000000 +0200
@@ -109,6 +109,9 @@
         except exception.UserNotFound:
             raise AssertionError('Invalid user / password')
 
+        if not user_id or not password:
+            raise AssertionError('Invalid user / password')
+
         try:
             conn = self.user.get_connection(self.user._id_to_dn(user_id),
                                             password)