$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gtk3.git /var/lib/mock/f41-build-859041-168533/root/chroot_tmpdir/scmroot/rubygem-gtk3
Cloning into '/var/lib/mock/f41-build-859041-168533/root/chroot_tmpdir/scmroot/rubygem-gtk3'...
$ git fetch origin 5ffb0a396a3522426f18cb2a0c92a8e2234cf293:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gtk3
 * [new ref]         5ffb0a396a3522426f18cb2a0c92a8e2234cf293 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5ffb0a3 4.2.4 entry