$ git clone -n https://src.fedoraproject.org/rpms/plasma-oxygen.git /var/lib/mock/f40-build-803689-144333/root/chroot_tmpdir/scmroot/plasma-oxygen
Cloning into '/var/lib/mock/f40-build-803689-144333/root/chroot_tmpdir/scmroot/plasma-oxygen'...
$ git fetch origin df2eb63b093740840f0ede98814cf448dd15be69:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/plasma-oxygen
 * [new ref]         df2eb63b093740840f0ede98814cf448dd15be69 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at df2eb63 6.0.3