Spotted by Kelson: https://bh.wikipedia.org/w/api.php?action=query&meta=siteinfo&siprop=general bh.wiki uses language code "bh", which doesn't appear to be valid ISO 639 http://www-01.sil.org/iso639-3/codes.asp?order=639_3&letter=b and never was http://www-01.sil.org/iso639-3/codes_retired.asp .
Names.php has:
'bh' => 'भोजपुरी', # Bihari macro language. Falls back to Bhojpuri (bho) 'bho' => 'भोजपुरी', # Bhojpuri
http://www-01.sil.org/iso639-3/macrolanguages.asp doesn't confirm
The wiki is already listed at https://meta.wikimedia.org/wiki/Special_language_codes as needing rename, but for now let's use the proper code.
See also: T41968: Bhojpuri wikipedia should start with 'bho' instead of 'bh' to avoid confusion with Bihari, https://bugzilla.redhat.com/show_bug.cgi?id=677570