$ git clone -n https://github.com/xcp-ng-rpms/mdadm /var/lib/mock/v8.3-incoming-10719-29267/root/chroot_tmpdir/scmroot/mdadm
Cloning into '/var/lib/mock/v8.3-incoming-10719-29267/root/chroot_tmpdir/scmroot/mdadm'...
$ git fetch origin c55376d4ddc41fb2498f70f68f922fc2a100a0e2:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/mdadm
 * [new ref]         c55376d4ddc41fb2498f70f68f922fc2a100a0e2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c55376d Import mdadm-4.2-5.xs8.src.rpm