When used with MW 1.35 links in the language selector (under "In other languages" in the left sidebar) seem wrong. For example, the link to the main page in French is fr:Main_Page/fr that links to a non-existing page and it does not correctly open Main_Page/fr.
I've been able to fix the problem by patching line 305 in Polyglot.php from:
$fakelinks = $lang . ':' . $t;
$fakelinks = $t;
however I'm not sure whether it's an appropriate solution or just a workaround.