$ git clone -n https://src.fedoraproject.org/rpms/rabbitmq-server.git /var/lib/mock/f41-build-side-1-2906993-34723/root/chroot_tmpdir/scmroot/rabbitmq-server
Cloning into '/var/lib/mock/f41-build-side-1-2906993-34723/root/chroot_tmpdir/scmroot/rabbitmq-server'...
$ git fetch origin 4c78962635839772615a3d6b25f3d2b2ee2b78c8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rabbitmq-server
 * [new ref]         4c78962635839772615a3d6b25f3d2b2ee2b78c8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4c78962 RabbitMQ doesn't support %{?_smp_mflags} properly (anymore?)