$ git clone -n https://src.fedoraproject.org/rpms/plymouth-kcm.git /var/lib/mock/f42-build-side-1-3566310-46733/root/chroot_tmpdir/scmroot/plymouth-kcm
Cloning into '/var/lib/mock/f42-build-side-1-3566310-46733/root/chroot_tmpdir/scmroot/plymouth-kcm'...
$ git fetch origin 758575e133a637280ff32bd1e2c202c9f1098eab:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/plymouth-kcm
 * [new ref]         758575e133a637280ff32bd1e2c202c9f1098eab -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 758575e 6.4.0