The http.File interface requires Readdir, which is used to list a folder in FileServer when index.html is not present.

Currently, packr's file.Readdir which comes from box.Open returns just a single entry, the directory name itself, see: https://github.com/gobuffalo/packd/blob/master/file.go#L41

This means that Readdir does not actually read the directory, making it impossible to use.

I specifically got caught with this trying to copy a packed folder to the filesystem recursively - Readdir was returning the same folder as its own child.