To reproduce, one needs to enter any Moscow address in Russian - nothing will be found. This was probably caused by my work on form encoding. KURL::init() works differently depending on what path is given to it - e.g. absolute paths like "/foo.html" get UTF-encoded twice! It is likely that this affects more than just XMLHttpRequest. Patch forthcoming.
<rdar://problem/5952342>
Created attachment 21269 [details] proposed fix
Committed in <http://trac.webkit.org/changeset/33966>.