Missing `Content-MD5` header for core downloads

$ curl -I https://downloads.wordpress.org/release/wordpress-4.6.1.zip
HTTP/1.1 200 OK
Server: nginx
Date: Thu, 24 Nov 2016 09:33:22 GMT
Content-Type: application/zip
Content-Length: 8650308
Connection: keep-alive
Cache-control: private
Content-Disposition: attachment; filename=wordpress-4.6.1.zip
Last-Modified: Wed, 07 Sep 2016 14:59:22 GMT
X-Frame-Options: SAMEORIGIN
X-nc: HIT lax 189
Accept-Ranges: bytes

The headerHeader The header of your site is typically the first thing people will experience. The masthead or header art located across the top of your page is part of the look and feel of your website. It can influence a visitor’s opinion about your content and you/ your organization’s brand. It may also look different on different screen sizes. was added 5 years ago in [dotorg5308]. [dotorg7078] added X-Accel-Redirect which may be the reason for the missing header now. To quote @dd32:

IIRC even when sent by PHPPHP PHP (recursive acronym for PHP: Hypertext Preprocessor) is a widely-used open source general-purpose scripting language that is especially suited for web development and can be embedded into HTML. http://php.net/manual/en/intro-whatis.php., when it’s a X-Accel-Redirect it needs to be whitelisted in nginxNGINX NGINX is open source software for web serving, reverse proxying, caching, load balancing, media streaming, and more. It started out as a web server designed for maximum performance and stability. In addition to its HTTP server capabilities, NGINX can also function as a proxy server for email (IMAP, POP3, and SMTP) and a reverse proxy and load balancer for HTTP, TCP, and UDP servers. https://www.nginx.com/... I think we’ve enabled it and never pushed a change into nginx..