$ git clone -n https://src.fedoraproject.org/rpms/libvirt.git /var/lib/mock/f40-build-2146974-50889/root/chroot_tmpdir/scmroot/libvirt
Cloning into '/var/lib/mock/f40-build-2146974-50889/root/chroot_tmpdir/scmroot/libvirt'...
$ git fetch origin 93a549eb1a21e6bbf507d05be7211dcb0897e505:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libvirt
 * [new ref]         93a549eb1a21e6bbf507d05be7211dcb0897e505 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 93a549e Bump and rebuild for xen 4.18.0, third attempt