it breaks Jetpack carousel lightbox

After I installed and enabled this plugin, clicking on images in a gallery (I’m using jetpack 2.5, no other gallery plugins) it just goes to the imagefile instead of showing it in lightbox.
After I disable this plugin lightbox works again.

With plugin: http://beta.zizkovkaraoke.com/photos-monopoly-19-august-2013/
Without: http://www.zizkovkaraoke.com/photos-monopoly-19-august-2013/

(The sites are slightly different, but I discovered the problem on the production site and had to disable the plugin there immediately of course.)

http://wordpress.org/plugins/relative-url/