Followup on Atomic composes

[Colin Walters]

From:
15:36:25 <dgilmore> walters: i have it working for the TC/RC process. I
need to change up a few things. not yet looked at doing it for
rawhide/branched yet

Are there any blockers to setting up the rawhide/branched parts? 
Anything I can help with?
In particular, will these composes write trees to the mirrors?

If we're only doing a tree compose for TC, things are highly likely not
to work because it'll be the first time we've run it in prod.

What I'm thinking about for a plan is: Dennis (and any help he needs)
work on the mainline rel-eng thread for F21.

In the meantime though, Atomic still needs a mechanism to *try* code
that's in development.  So I may look at having the internal compose
server be a "pull from COPR" type thing and thus be a remix (again), but
improve on the current situation by mirroring to dl.fp.org or so.