User is not notified that a user cannot be found while adding users to groups

When a admin attempts to add a user that does not exist to a group, in the following page : http://

/admin/users/adduserstogroup.action

They are not advised that the user could not be found

Screenshot shows expected behavior (works in 3.5), however in the tested versions (4.0 , 4.2.6) this message does not appear and there is no advice that the user cannot be found.