bug#1285: 23.0.60; minibuffer-complete and `C-x d'

[Stephen Berman]

In GNU Emacs 23.0.60.12 (i686-pc-linux-gnu, GTK+ Version 2.12.9)
 of 2008-10-25 on escher

When I type `C-x d <something> TAB', where `<something>' is any sequence
of characters, then if `<something>' can complete to more than one
directory name, then the *Completions* buffer displays only those
directory names, but no non-directory file names.  But if `<something>'
can complete to a non-directory file name, then it does.  For example,
on my system `C-x d /usr/lib/libv TAB' completes to '/usr/lib/libvisual'
and after a second TAB the *Completions* buffer displays:

Possible completions are:
libvisual-0.4/
libvisual/

But `C-x d /usr/lib/libvisual-0.4. TAB' completes to 
'/usr/lib/libvisual-0.4.so.0'
and after a second TAB the *Completions* buffer displays:

Possible completions are:
libvisual-0.4.so.0
libvisual-0.4.so.0.0.0

Typing `C-x C-f /usr/lib/libvis TAB' completes to '/usr/lib/libvisual'
and after a second TAB the *Completions* buffer displays:

Possible completions are:
libvisual-0.4.so.0                 libvisual-0.4.so.0.0.0
libvisual-0.4/                     libvisual/

(In Emacs 22.2, `C-x d [or: C-x C-f] /usr/lib/libvis TAB' does just the
latter.)

This is with -Q, and I get the same behavior with completion-styles set
to any of `basic', `emacs21', emacs22', or `partial-completion'.