Avoid sending "Connection: keep-alive" when shutting down. When a worker process is shutting down, keepalive is not used: this is checked before the ngx_http_set_keepalive() call in ngx_http_finalize_connection(). Yet the "Connection: keep-alive" header was still sent, even if we know that the worker process is shutting down, potentially resulting in additional requests being sent to the connection which is going to be closed anyway. While clients are expected to be able to handle asynchronous close events (see ticket #1022), it is certainly possible to send the "Connection: close" header instead, informing the client that the connection is going to be closed and potentially saving some unneeded work. With this change, we additionally check for worker process shutdown just before sending response headers, and disable keepalive accordingly.