$ git clone -n https://src.fedoraproject.org/rpms/mcstrans.git /var/lib/mock/f42-build-3272237-41305/root/chroot_tmpdir/scmroot/mcstrans
Cloning into '/var/lib/mock/f42-build-3272237-41305/root/chroot_tmpdir/scmroot/mcstrans'...
$ git fetch origin dba2684ba4dad447c4ade52812c72cd79ae0168a:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mcstrans
 * [new ref]         dba2684ba4dad447c4ade52812c72cd79ae0168a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at dba2684 SELinux userspace 3.8 release