Something is breaking my links with %E2%80%8E

I checked the source of this post: http://foodandchatter.co.za/zama-memela/ and the source code reads:

<a title="GreenPop" href="http://www.greenpop.org/?" target="_blank">Greenpop festival in Zambia</a>

yet when you open that post and click the link you end up here: http://www.greenpop.org/%E2%80%8E

This is somewhat of a mystery to me as I'm struggling to figure out who the culprit is.

Broken Link Checker reported this to me and I have since ruled out ngx_pagespeed. To see the post with ngx_pagespeed turned off try this url: http://foodandchatter.co.za/zama-memela/?PageSpeed=off

I've also tried this while being logged in/out and with different browsers. Chrome, Firefox and Safari all display the same problem on MAC OSX.

Any ideas at all?