$ git clone -n https://src.fedoraproject.org/rpms/libtbox.git /var/lib/mock/f41-build-856291-167528/root/chroot_tmpdir/scmroot/libtbox
Cloning into '/var/lib/mock/f41-build-856291-167528/root/chroot_tmpdir/scmroot/libtbox'...
$ git fetch origin 1902f46fa28e21940fb265631b879f23537ca15e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libtbox
 * [new ref]         1902f46fa28e21940fb265631b879f23537ca15e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1902f46 Update to 1.7.6