D4640: narrow: add test showing that local-to-local narrow clones don't work

[Yuya Nishihara]

> +  $ rm -r narrow-via-localpeer
> +  rm: narrow-via-localpeer: $ENOENT$
> +  [1]

Changed this to `rm -Rf` and queued, thanks. It appears that GNU rm shows
friendlier message.