$ git clone -n https://github.com/xcp-ng-rpms/sm.git /var/lib/mock/v8.3-u-dtt1-10717-29268/root/chroot_tmpdir/scmroot/sm
Cloning into '/var/lib/mock/v8.3-u-dtt1-10717-29268/root/chroot_tmpdir/scmroot/sm'...
$ git fetch origin f3bf61aff71b48b25c6201d91641c2500c7a9902:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/sm
 * [new ref]         f3bf61aff71b48b25c6201d91641c2500c7a9902 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f3bf61a test-build for v8.3-u-dtt1