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I've made an edit to bring over the change we made to decrease the prominence of the native names on Template:Infobox former country (see the discussion). Doing so here works perfectly well in the dozen or so articles I've checked that transclude this template, but they have broken how the template is displayed on its own page.
I can't see what it could be that is causing that problem, however. As it's 2am here and I have things to do tomorrow (and as it's not actually affecting anything in the Article namespace, as far as I can see), could someone take a look at the diff to see what I did to break it, please?