$ git clone -n https://src.fedoraproject.org/rpms/groonga.git /var/lib/mock/f42-build-side-1-3506338-45996/root/chroot_tmpdir/scmroot/groonga
Cloning into '/var/lib/mock/f42-build-side-1-3506338-45996/root/chroot_tmpdir/scmroot/groonga'...
$ git fetch origin d208a2dd94ff4794ad40f2ff4847051ba6985be6:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/groonga
 * [new ref]         d208a2dd94ff4794ad40f2ff4847051ba6985be6 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d208a2d 15.0.2