Fix gang scheduling and license release logic

Fix gang scheduling and license release logic if single node job killed on
    bad node. Notifying gang and releasing licences is normally done when
    the epilog completion happens, but if the node(s) assigned to a job are
    all down, that does not happen. This results in the licenses being
    reserved indefinitely and the gang scheduler being left with a bad
    (old) job pointer that can result in various failure modes
bug 2867