$ git clone -n https://src.fedoraproject.org/rpms/buildbox.git /var/lib/mock/f41-build-853933-166804/root/chroot_tmpdir/scmroot/buildbox
Cloning into '/var/lib/mock/f41-build-853933-166804/root/chroot_tmpdir/scmroot/buildbox'...
$ git fetch origin c56428f7d3bb6e4bbdf5c4c3449a9105f5a19a53:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/buildbox
 * [new ref]         c56428f7d3bb6e4bbdf5c4c3449a9105f5a19a53 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c56428f Update to 1.2.20