$ git clone -n https://src.fedoraproject.org/rpms/xz.git /var/lib/mock/f41-build-807991-145577/root/chroot_tmpdir/scmroot/xz
Cloning into '/var/lib/mock/f41-build-807991-145577/root/chroot_tmpdir/scmroot/xz'...
$ git fetch origin 91940317881fb3fd42e1cd9453e52a62b0a4deb1:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/xz
 * [new ref]         91940317881fb3fd42e1cd9453e52a62b0a4deb1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9194031 Use %{epoch} in runtime Requires