こんにちは、鯨井貴博@opensourcetechです。
4/19、nginx mainline の最新バーション 1.9.15がリリースされました。

更新内容は、以下となります。
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Changes with nginx 1.9.15 19 Apr 2016
*) Bugfix: "recv() failed" errors might occur when using HHVM as a
FastCGI server.
*) Bugfix: when using HTTP/2 and the "limit_req" or "auth_request"
directives a timeout or a "client violated flow control" error might
occur while reading client request body; the bug had appeared in
1.9.14.
*) Workaround: a response might not be shown by some browsers if HTTP/2
was used and client request body was not fully read; the bug had
appeared in 1.9.14.
*) Bugfix: connections might hang when using the "aio threads"
directive.
Thanks to Mindaugas Rasiukevicius.
From http://nginx.org/en/CHANGES
機能追加はありませんが、bugfixがあるのでバージョンアップしておきたいですね。