Our app allows the user to key in a string, and it queries the Commons MediaWiki API for categories beginning with that string. However, the API sometimes returns nonexistent categories when we query it.
For instance, if we query https://commons.wikimedia.org/w/api.php?action=query&list=allcategories&acprefix=badge&aclimit=25 for categories beginning with 'badge', the first result is Badge. However, https://commons.wikimedia.org/wiki/Category:Badge does not exist and does not appear to have ever existed.
Are we doing something wrong, or is this a bug in the Commons MediaWiki API?
(This is currently being discussed at https://github.com/nicolas-raoul/apps-android-commons/issues/22 )