James Alexander, 17/01/2013 02:13:
Sorry, I didn't actually finish ;) If I had to make a guess it would seem like they are following and reading interwiki links directly (since the only place we have that type of structure is for interwiki links) but I have no evidence for that other then a hunch.
https://bugzilla.wikimedia.org/show_bug.cgi?id=26115
Nemo