execution of post_action each time breaks a keepalive connection to upstream

[Sergey Brester]

> Hello!
> 
> On Thu, May 07, 2015 at 12:51:33PM +0200, Sergey Brester wrote:
> 
>> Hi all, I've found that use of "post_action @named_post" always (each 
>> time) closes a upstream connection (despite of keepalive).
> 
> In short:
> 
> - post_action is a dirty hack and undocumented on purpose, avoid
> using it;

Undocumented in the long term or just still not?
Because meanwhile it will be used from "half" world... I know at least a 
dozen companies, using that.

> 
> - as long as an upstream response is complete after receiving a
> header, upstream keepalive should work even with post_action; it
> might be tricky to ensure this with fastcgi though.

What confuses me, that a header_only subrequest to fastcgi works fine!
And what I mean was, it can be not "post_action" self, but possible all 
"header_only" requests via ngx_http_named_location etc. so in this case 
many things are affected (including third-party modules).

Thx, Serg.