avoid tickling race condition with common keep alive timeout setting
    
    The default KeepAliveTimeout in Apache httpd 2.4 is 5 seconds. Sleeping for that
    same time and then resuming calls can tickle a race condition.
    
    The previous commit /should/ catch that now, but there's no sense hitting that
    error so often.
    
    See also: https://github.com/mikem23/keepalive-race