$ git clone -n https://src.fedoraproject.org/rpms/R-msm.git /var/lib/mock/f42-build-side-1-3501311-45974/root/chroot_tmpdir/scmroot/R-msm
Cloning into '/var/lib/mock/f42-build-side-1-3501311-45974/root/chroot_tmpdir/scmroot/R-msm'...
$ git fetch origin f6eb69f4e9c94fe86ebb37722efd1a12e00ac9c5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-msm
 * [new ref]         f6eb69f4e9c94fe86ebb37722efd1a12e00ac9c5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f6eb69f Update to latest version