Resend message while waiting for ostree ref
    
    If the signing machinery crashes, we don't want to wait forever. This
    way at least we can shout for help periodically.
    
    Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>
    Fixes: https://pagure.io/pungi/issue/1350
    JIRA: COMPOSE-4166