$ git clone -n https://src.fedoraproject.org/rpms/galera.git /var/lib/mock/f39-build-2303746-56967/root/chroot_tmpdir/scmroot/galera
Cloning into '/var/lib/mock/f39-build-2303746-56967/root/chroot_tmpdir/scmroot/galera'...
$ git fetch origin 66bd1fc4794b02c41f412bf4d1e614fcc70ffbf3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/galera
 * [new ref]         66bd1fc4794b02c41f412bf4d1e614fcc70ffbf3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 66bd1fc Rebuild