When using the search plugin, results are linked to `foo/bar/index.html`,
whether or not use_dirs is enabled; when use_dirs is enabled, the link should
point to `foo/bar/` instead.

> Similarly, after editing a page `foo/bar/`, the user is redirected to
> `foo/bar/index.html?updated` instead of `foo/bar/?updated`.
> --[Jason Blevins](http://jblevins.org/)