--- a/hooks/security.py	Thu Jan 16 12:21:05 2014 +0100
+++ b/hooks/security.py	Thu Jan 16 13:50:26 2014 +0100
@@ -60,7 +60,8 @@
                 # nothing.
                 continue
             if perms == ():
-                # That means an immutable attribute.
+                # That means an immutable attribute; as an optimization, avoid
+                # going through check_perm.
                 raise Unauthorized(action, str(rdef))
             rdef.check_perm(session, action, eid=eid)