Avoid resetting download status on 503
On comment:31:ticket:20499 , Teor notes:
If we really do want every failure to result in a schedule increment, we have to remove the following code:
download_status_increment_failure: {{{ /* only count the failure if it's permanent, or we're a server */ if (status_code != 503 || server) { if (dls->n_download_failures < IMPOSSIBLE_TO_DOWNLOAD-1) ++dls->n_download_failures; } }}}
Because combined with this code in download_status_schedule_get_delay, it causes a reset on every 503: {{{ /* Check if we missed a reset somehow */ if (dls->last_backoff_position > dls_schedule_position) { dls->last_backoff_position = 0; dls->last_delay_used = 0; } }}}
Which is exactly what we don't want when relays are busy - imagine clients doing an automatic reset every time they DoS a relay...