I can confirm this works as expected on group2/wmf.31 but is broken on wmf.32. Also it still works in all versions under MonoBook, which suggests it is a bug in Vector that was introduced in the new branch.
Issue on https://www.mediawiki.org/
|Vector (wmf.32)||MonoBook (wmf.31)||Vector (wmf.31)|
Issue on https://wikitech.wikimedia.org/