User blog comment:Rappy 4187/Technical Update: February 5, 2013/@comment-1280533-20130206180101/@comment-1280533-20130207095955

I think I'll send it in as a bug, as this is also causing to not work, which is also annoying. Besides, the only time when would be a useful piped addition is when categorising pages in project, template or other namespaces, and the category module is not used for those.