$ curl -I http://lcamtuf.coredump.cx/squirrel/ HTTP/1.1 200 OK Date: Thu, 11 Aug 2016 05:18:00 GMT Server: Apache Last-Modified: Mon, 19 Sep 2011 23:31:49 GMT Accept-Ranges: bytes Content-Length: 135938 Content-Type: text/html
I guess browsers only forbid ignoring Content-Type for stuff like JS, then. For JPEG it's probably not a security concern.