fixed #1204, updating session when add_membership

gluon/tools.py

@@ -4387,9 +4387,6 @@ class Auth(object):
             return record.id
         else:
             id = membership.insert(group_id=group_id, user_id=user_id)
-        if role:
-            self.user_groups[group_id] = role
-        else:
         self.update_groups()
         self.log_event(self.messages['add_membership_log'],
                        dict(user_id=user_id, group_id=group_id))