Keepalive connections now respect lingering_timeout on shutdown. During graceful shutdown keepalive connections are now closed only after at least lingering_timeout of inactivity. To do so, c->idle is only set on keepalive connections after lingering_timeout expires. This ensures that the connection close race will less likely result in connections being reset when a client sends a request at the same time when the connection is closed by ngx_close_idle_connections() during graceful shutdown.