Changes with nginx 1.7.8 02 Dec 2014
*) Change: now the "If-Modified-Since", "If-Range", etc. client request header lines are passed to a backend while caching if nginx knows in advance that the response will not be cached (e.g., when using proxy_cache_min_uses).
*) Change: now after proxy_cache_lock_timeout nginx sends a request to a backend with caching disabled; the new directives "proxy_cache_lock_age", "fastcgi_cache_lock_age", "scgi_cache_lock_age", and "uwsgi_cache_lock_age" specify a time after which the lock will be released and another attempt to cache a response will be made.
*) Change: the "log_format" directive can now be used only at http level.
*) Feature: the "proxy_ssl_certificate", "proxy_ssl_certificate_key", "proxy_ssl_password_file", "uwsgi_ssl_certificate", "uwsgi_ssl_certificate_key", and "uwsgi_ssl_password_file" directives. Thanks to Piotr Sikora.
*) Feature: it is now possible to switch to a named location using "X-Accel-Redirect". Thanks to Toshikuni Fukaya.
*) Feature: now the "tcp_nodelay" directive works with SPDY connections.
*) Feature: new directives in vim syntax highliting scripts. Thanks to Peter Wu.
*) Bugfix: nginx ignored the "s-maxage" value in the "Cache-Control" backend response header line. Thanks to Piotr Sikora.
*) Bugfix: in the ngx_http_spdy_module. Thanks to Piotr Sikora.
*) Bugfix: in the "ssl_password_file" directive when using OpenSSL 0.9.8zc, 1.0.0o, 1.0.1j.
*) Bugfix: alerts "header already sent" appeared in logs if the "post_action" directive was used; the bug had appeared in 1.5.4.
*) Bugfix: alerts "the http output chain is empty" might appear in logs if the "postpone_output 0" directive was used with SSI includes.
*) Bugfix: in the "proxy_cache_lock" directive with SSI subrequests. Thanks to Yichun Zhang.