commit d8ec4910ce8b69c5dac3739b5a09503d49521340
author Valentin Bartenev <vbart@nginx.com> Wed May 30 12:30:03 2012 +0000
committer Valentin Bartenev <vbart@nginx.com> Wed May 30 12:30:03 2012 +0000
tree f304884bd05e2a17e44da8d0f56536df74af353e
parent 94d8df609872916b4899f12269633447dd06e182

Fixed returned value handling from the cookie rewrite handler.

If the "proxy_cookie_domain" or "proxy_cookie_path" directive is used and there
are no matches in Set-Cookie header then ngx_http_proxy_rewrite_cookie() returns
NGX_DECLINED to indicate that the header was not rewritten. Returning this value
further from the upstream headers copy handler resulted in 500 error response.

See here for report:
http://mailman.nginx.org/pipermail/nginx/2012-May/033858.html