I just signed up for the trial of CircleCI, not least because I’d like to use it for an Open Source OS X project of mine. Most of my projects are hosted in Bitbucket, rather than Github, primarily because I prefer Mercurial to Git. Unfortunately, on the “Add Project” page, when I click on my Bitbucket team, I see “No matching repos for organization”.
mercurial isn’t supported
That would certainly explain it, but you can’t claim to support Bitbucket without supporting Mercurial. Bitbucket was originally Mercurial only!