In bug 825821, we stopped hard-coding the mobile site in the wikipedia plugin, so that wp can work it's magic on whether it should show you the mobile or the desktop site. Mind porting that change over to your localization? Milos might be able to help. We'll want a patch for the change, and get Milos to review it, or he'll just write the patch himself. I'm filing this independent of whether we're shipping Fennec, or are close doing so.
On second thoughts, this will be fixed in bug 885079 with other searchplugins, so let's consider this as a dupe instead of blocking it.