Keepalive: better fastcgi testing.
Keepalive: better fastcgi testing.

With previous fastcgi keepalive patches minimal number of bytes that should
be fed to input filter (pipe->length) wasn't always set correctly.  Try
harder to catch this.

Reported by:	Denis F. Latypoff

catap/ngx_http_upstream_keepalive,catap/ngx_http_upstream_keepalive