desktop.el assumes dired-directory is a string

[Peter S Galbraith]

In GNU Emacs 21.3.2 (i386-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2003-04-24 on raven, modified by Debian
configured using `configure  i386-linux --prefix=/usr --sharedstatedir=/var/lib 
--libexecdir=/usr/lib --localstatedir=/var/lib --infodir=/usr/share/info 
--mandir=/usr/share/man --with-pop=yes --with-x=yes --with-x-toolkit=athena 
--without-gif'
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: C
  locale-coding-system: nil
  default-enable-multibyte-characters: nil

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

desktop.el's desktop-save may fail (for example) with:

  expand-file-name(("/" "/usr/share/gri/2.12.5/startup.msg" ...)
  (cons (expand-file-name dired-directory) (cdr (nreverse ...)))

in

(defun desktop-buffer-dired-misc-data ()
  (if (eq major-mode 'dired-mode)
      (cons
       (expand-file-name dired-directory)
       (cdr
        (nreverse
         (mapcar
          (function car)
          dired-subdir-alist))))))

it assumes that `dired-directory' is a string holding the directory
name.  But it can also a a list to files to display.

This had triggered a bug in the package apt-utils that uses dired
with this method.

Thanks,
-- 
Peter S. Galbraith, Debian Developer          <psg@debian.org>
                                 http://people.debian.org/~psg
GPG key 1024/D2A913A1 - 97CE 866F F579 96EE  6E68 8170 35FF 799E