$ git clone -n https://src.fedoraproject.org/rpms/plasma-milou.git /var/lib/mock/f42-build-side-1-3578400-46814/root/chroot_tmpdir/scmroot/plasma-milou
Cloning into '/var/lib/mock/f42-build-side-1-3578400-46814/root/chroot_tmpdir/scmroot/plasma-milou'...
$ git fetch origin 81dc6e60f2de27cfd9167860cda0da8bef30fee0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/plasma-milou
 * [new ref]         81dc6e60f2de27cfd9167860cda0da8bef30fee0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 81dc6e6 6.4.1