Changes with nginx 1.4.5 11 Feb 2014
*) Bugfix: the $ssl_session_id variable contained full session serialized instead of just a session id. Thanks to Ivan Ristić.
*) Bugfix: client connections might be immediately closed if deferred accept was used; the bug had appeared in 1.3.15.
*) Bugfix: alerts "zero size buf in output" might appear in logs while proxying; the bug had appeared in 1.3.9.
*) Bugfix: a segmentation fault might occur in a worker process if the ngx_http_spdy_module was used.
*) Bugfix: proxied WebSocket connections might hang right after handshake if the select, poll, or /dev/poll methods were used.
*) Bugfix: a timeout might occur while reading client request body in an SSL connection using chunked transfer encoding.
*) Bugfix: memory leak in nginx/Windows.