It's possible to have the JavaScript search for " → " and stop any string at that point, but it feels a bit ugly, so I have omitted that.
What would happen if someone was genuinely looking for http://en.wikipedia.org/w/index.php?title=%E2%86%90%E2%86%93%E2%86%91%E2%86%...
:P
I knew there was a reason it felt a bit wrong, and that example is probably it! ;-)
And by the way, if I copy and paste in the "←↓↑→" (i.e. the 4 arrow symbols in case an email system munges it), then the search suggest does give the "Dance Dance Revolution" redirect as it's suggestion ;-)
All the best, Nick.