ngx_http_upstream_process_non_buffered_request recv question

[gaoyan09]

thx

I see it. 
This do keep sending to client if upstream connection eof or error, only
finalize request when u->busy_bufs == NULL, as all recv buffers had send to
client

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,268278,268288#msg-268288