Citiranje Smolenski Nikola smolensk@EUnet.rs:
It gets even funnier if you go to https://www.wikidata.org/wiki/Q3711?uselang=sr-el since now you get Serbian three times: as "srpski (latinica)", "Serbian (Cyrillic script)" and "српски". It appears that the first is sr-el, the second is sr-ec and the third is the new sr-cyrl.
And even funnier if you go to https://www.wikidata.org/wiki/Q3711?uselang=sr-latin . Now you get four options: "sr-latin", "Serbian (Latin script)", "Serbian (Cyrillic script)", and "српски". This appears to be a mixture of https://phabricator.wikimedia.org/T39459 and new codes still not being recognized in URLs.