$ git clone -n https://src.fedoraproject.org/rpms/cups-filters.git /var/lib/mock/f38-build-side-42-init-devel-576040-26000/root/chroot_tmpdir/scmroot/cups-filters
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-576040-26000/root/chroot_tmpdir/scmroot/cups-filters'...
$ git fetch origin ba20eaa5fa4bb7414abb3ba910a51b4a447815ad:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/cups-filters
 * [new ref]         ba20eaa5fa4bb7414abb3ba910a51b4a447815ad -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at ba20eaa use epoch to ensure clean upgrade path, because I didn't read FPG carefully