$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rsvg2.git /var/lib/mock/f40-build-2639337-66352/root/chroot_tmpdir/scmroot/rubygem-rsvg2
Cloning into '/var/lib/mock/f40-build-2639337-66352/root/chroot_tmpdir/scmroot/rubygem-rsvg2'...
$ git fetch origin afaaf82b9a180f288417b0e943b46eb974efb479:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rsvg2
 * [new ref]         afaaf82b9a180f288417b0e943b46eb974efb479 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at afaaf82 4.2.1 entry