$ git clone -n https://src.fedoraproject.org/rpms/libtiff.git /var/lib/mock/f41-build-side-1-2645554-27108/root/chroot_tmpdir/scmroot/libtiff
Cloning into '/var/lib/mock/f41-build-side-1-2645554-27108/root/chroot_tmpdir/scmroot/libtiff'...
$ git fetch origin 550f8063ac5f128dbc35ba9700a09aa0d2d36d50:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libtiff
 * [new ref]         550f8063ac5f128dbc35ba9700a09aa0d2d36d50 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 550f806 make it possible to share spec file in other branches