Candidate composes (as opposed to nightly composes) for Branched are synced to https://dl.fedoraproject.org/pub/alt/stage/ after they're built. This is supposed to be the preferred download location for them (rather than kojipkgs).

However, there is currently no fedmsg emitted when this happens, so automated systems have no good way to know when a candidate compose has been synced and is available from stage/. It would be good if there was a fedmsg for this (probably a compose one).

@puiterwijk