JPG images are broken when using mozjpeg

[niutech]

Some JPG images are broken and doesn't appear in the latest Firefox when using Janus, e.g. http://mozliwosci.com/blog/wp-content/uploads/2012/08/tvp_estetyka_top.jpg Response headers:

HTTP/1.1 200 OK
Date: Thu, 28 Jan 2016 16:52:56 GMT
Server: Apache
Last-Modified: Fri, 31 Aug 2012 16:57:48 GMT
Etag: "4dd6ab2-acf6-4c892b10c5b00"
Accept-Ranges: bytes
Content-Type: image/jpeg
Via: janus/0.7.0
x-original-content-length: 44278
X-Firefox-Spdy: 3.1

There is missing Content-Length. Debug log does not show anything wrong, just: info: [worker 8960] [INFO] Recompressing JPEG... It happens only when using mozjpeg. libjpeg-turbo works fine.