$ git clone -n https://src.fedoraproject.org/rpms/plasma-milou.git /var/lib/mock/f42-build-side-1-3510461-46033/root/chroot_tmpdir/scmroot/plasma-milou
Cloning into '/var/lib/mock/f42-build-side-1-3510461-46033/root/chroot_tmpdir/scmroot/plasma-milou'...
$ git fetch origin d7aff21dd92e9c50f12dafd62532bcf2e9eecf67:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/plasma-milou
 * [new ref]         d7aff21dd92e9c50f12dafd62532bcf2e9eecf67 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d7aff21 6.3.4