$ git clone -n https://src.fedoraproject.org/rpms/plasma-nano.git /var/lib/mock/f42-build-side-1-3566302-46733/root/chroot_tmpdir/scmroot/plasma-nano
Cloning into '/var/lib/mock/f42-build-side-1-3566302-46733/root/chroot_tmpdir/scmroot/plasma-nano'...
$ git fetch origin 51136ba5c345925ddcbed948062a4999f6a2845d:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/plasma-nano
 * [new ref]         51136ba5c345925ddcbed948062a4999f6a2845d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 51136ba 6.4.0