$ git clone -n https://github.com/xcp-ng-rpms/amd-microcode.git /var/lib/mock/v8.3-incoming-8851-27784/root/chroot_tmpdir/scmroot/amd-microcode
Cloning into '/var/lib/mock/v8.3-incoming-8851-27784/root/chroot_tmpdir/scmroot/amd-microcode'...
$ git fetch origin 4280957777af57224dd139c35a47b1077b85fcb1:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/amd-microcode
 * [new ref]         4280957777af57224dd139c35a47b1077b85fcb1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4280957 Merge pull request #6 from xcp-ng-rpms/gdy-xsa471