After they appear in kojipkgs like all other Pungi composes, the two-week Atomic composes are synced to https://dl.fedoraproject.org/pub/alt/atomic/testing . The ones that are promoted to 'stable' are copied (or linked? whichever) into https://dl.fedoraproject.org/pub/alt/stable .

We should handle both these locations as two new Release classes (...sigh), with attendant logic in get_release (...double sigh) to try and find Atomic composes there before falling back on the kojipkgs location, similar to how we handle candidate composes for Branched.