mpm event assertion failures

[Stefan Eissing]

Also, while running the http2 test suite, I get repeated assert failures in 
event.c:1230

if (rv != APR_SUCCESS && !APR_STATUS_IS_EEXIST(rv)) {
->  AP_DEBUG_ASSERT(0);
    TO_QUEUE_REMOVE(cs->sc->wc_q, cs);
    apr_thread_mutex_unlock(timeout_mutex);
    ap_log_error(APLOG_MARK, APLOG_ERR, rv, ap_server_conf, APLOGNO(03465)
                 "process_socket: apr_pollset_add failure for "
                 "write completion");
    close_connection(cs);
    signal_threads(ST_GRACEFUL);
}

Seems something is fishy with the recent changes.

Kind regards,
Stefan