bug#8256: widget-complete does not complete for type 'directory onw32

[Drew Adams]

>       (defcustom my-dir nil "doc" :type 'directory)
> 
>   M-x customize-option RET my-dir RET

You get a type mismatch, of course, since nil is not a directory.

>   Place point in the directory value field and erase "nil" 
>   that is there.  Now in the empty directory value field
>   press ESC-TAB. This fails

Try again, with a valid directory as the default value - e.g. "c:/foo/"

Keep in mind too that the completion uses `default-directory'.  Dunno whether
that's always appropriate, but that's what it uses.

But I agree that regardless of the initial type mismatch, you should be able to
type a legitimate directory prefix and get completion.