$ git clone -n https://src.fedoraproject.org/rpms/libvirt.git /var/lib/mock/f42-build-863146-171455/root/chroot_tmpdir/scmroot/libvirt
Cloning into '/var/lib/mock/f42-build-863146-171455/root/chroot_tmpdir/scmroot/libvirt'...
$ git fetch origin b94faf01a5603dbafe574f92b94fa7cce0fc85a7:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libvirt
 * [new ref]         b94faf01a5603dbafe574f92b94fa7cce0fc85a7 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b94faf0 libvirt-10.10.0-1