Last modified: 2014-09-11 19:43:46 UTC
Given i.e. the page "ácido" and its hex sortkey 272b372d4301868d08010a00 retrieved through prop=categories, then packed and url-encoded, the request http://pl.wiktionary.org/w/api.php?action=query&list=categorymembers&format=xml&cmtitle=Kategoria%3Ahiszpa%C5%84ski%20%28indeks%29&cmprop=title|sortkey&cmlimit=10&cmsort=sortkey&cmdir=desc&cmstartsortkey=%27%2B7-C%01%86%8D%08%01%0A%00 doesn't start listing from "ácido" (it should be on the top).
I wish cmsortkey didn't take input in binary; I suspect what's happening here is that some layer is trying to interpret the binary characters as UTF-8 and thereby screwing them up. I think the real fix here will be deprecating cmstartsortkey and cmendsortkey in favor of something like cmstarthexsortkey and cmendhexsortkey that take the input hex-encoded.
Change 159746 had a related patch set uploaded by Anomie: API: Deprecate binary sortkey input in ApiQueryCategoryMembers https://gerrit.wikimedia.org/r/159746
Change 159746 merged by jenkins-bot: API: Deprecate binary sortkey input in ApiQueryCategoryMembers https://gerrit.wikimedia.org/r/159746
This should be deployed to WMF wikis with 1.24wmf22, see https://www.mediawiki.org/wiki/MediaWiki_1.24/Roadmap for the schedule.
