$ git clone -n https://src.fedoraproject.org/rpms/libplasma.git /var/lib/mock/f42-build-side-1-3584348-46893/root/chroot_tmpdir/scmroot/libplasma
Cloning into '/var/lib/mock/f42-build-side-1-3584348-46893/root/chroot_tmpdir/scmroot/libplasma'...
$ git fetch origin fb4aee21f2621a8f60813b103736380ac7d61b11:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/libplasma
 * [new ref]         fb4aee21f2621a8f60813b103736380ac7d61b11 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at fb4aee2 6.4.2