$ git clone -n https://src.fedoraproject.org/rpms/xz.git /var/lib/mock/f40-build-2648559-66789/root/chroot_tmpdir/scmroot/xz
Cloning into '/var/lib/mock/f40-build-2648559-66789/root/chroot_tmpdir/scmroot/xz'...
$ git fetch origin 2f4be0bc640b9d30ef241e5985970760b112f1ba:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xz
 * [new ref]         2f4be0bc640b9d30ef241e5985970760b112f1ba -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2f4be0b Use %{epoch} in runtime Requires