Jehan commented:
@averi I guess it's kind of a hard-requirement since we want our builds to be either on our own servers or on trusted/transparent build servers. Since we don't have any macOS server machine (and AFAIK macOS builds can only be done on macOS machines, not because of technical limitations, but for license issues), we'd have to rely on one of these build companies out there which provide for-free service to FLOSS projects. And apparently all of them can only pull from github repositories (I assume they use some sort of API). Well at least that's what I am told.
Our current macOS build maintainer already use the services of Circle CI.
So yeah, it would be nice if infrastructure projects could be mirrored as well, unless you think this is better suited under the GNOME group, which would make things simpler of course.