Changes with nginx 1.11.6 15 Nov 2016
*) Change: format of the $ssl_client_s_dn and $ssl_client_i_dn variables has been changed to follow RFC 2253 (RFC 4514); values in the old format are available in the $ssl_client_s_dn_legacy and $ssl_client_i_dn_legacy variables.
*) Change: when storing temporary files in a cache directory they will be stored in the same subdirectories as corresponding cache files instead of a separate subdirectory for temporary files.
*) Feature: EXTERNAL authentication mechanism support in mail proxy. Thanks to Robert Norris.
*) Feature: WebP support in the ngx_http_image_filter_module.
*) Feature: variables support in the "proxy_method" directive. Thanks to Dmitry Lazurkin.
*) Feature: the "http2_max_requests" directive in the ngx_http_v2_module.
*) Feature: the "proxy_cache_max_range_offset", "fastcgi_cache_max_range_offset", "scgi_cache_max_range_offset", and "uwsgi_cache_max_range_offset" directives.
*) Bugfix: graceful shutdown of old worker processes might require infinite time when using HTTP/2.
*) Bugfix: in the ngx_http_mp4_module.
*) Bugfix: "ignore long locked inactive cache entry" alerts might appear in logs when proxying WebSocket connections with caching enabled.
*) Bugfix: nginx did not write anything to log and returned a response with code 502 instead of 504 when a timeout occurred during an SSL handshake to a backend.