Make buildSRPMFromSCM faster?

[Adam Jackson]

On Sat, 2014-07-19 at 12:30 +0100, Richard W.M. Jones wrote:
> The first step of most Koji builds is buildSRPMFromSCM, where a
> .src.rpm file is built from the git repo.
> 
> Currently this involves completely building a mock buildroot
> containing all the BuildRequires, and running `rpmbuild -bs'.  This
> takes many minutes (especially when arm is chosen as a builder).

We really ought to just set up a channel populated only by actually
performant hardware that only accepts buildSRPMfromSCM jobs.

And then also fix https://fedorahosted.org/koji/ticket/276 so that the
job's output is deterministically good for all architectures, thus
avoiding the "but you should make sure it works if you do build the srpm
on arm" argument.

- ajax