fastcgi_cache_bypass and 502 Bad Gateway

[kaspars]

Using Nginx 0.8.54.

I'm trying to use fastcgi_cache_bypass with an HTTP header for Nginx to
request a new response from the backend and cache it.

[code]
if ($http_cookie ~*
"comment_author_|wordpress_(?!test_cookie)|wp-postpass_" ) {
  set $donot_cache 1;
}

fastcgi_cache   cachetitle;
fastcgi_cache_key   $scheme$host$request_uri;
fastcgi_no_cache   $donot_cache; # do no cache at all
fastcgi_cache_bypass   $http_cache_bypass; # bypass cache and cache the
new response
fastcgi_cache_use_stale  error timeout invalid_header http_500;
fastcgi_cache_min_uses  1;
[/code]

It does seem to work -- I see a fresh page returned from the backend,
but on the second request without the header I get a 502 Bad Gateway
response.

I also noticed that on Nginx wiki page there is no reference to 
fastcgi_cache_bypass, although I saw it there just a few days ago.

Is this feature being removed or postponed for later? Is it available in
the latest dev version?

Kaspars
http://konstruktors.com

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,173795,173795#msg-173795