dired-do-compress overwrites files without asking

[Sven Joachim]

In Dired, if both an uncompressed file (say foo) and a compressed
version of it (foo.gz) exist, typing 'Z' (dired-do-compress) with
point at the 'foo' file has the dangerous effect of overwriting
'foo.gz' without asking.  OTOH, typing 'Z' with point at 'foo.gz'
fails to uncompress the file, displaying an error message by gunzip.

In GNU Emacs 22.0.50.1 (i486-pc-linux-gnu, X toolkit, Xaw3d scroll bars)
 of 2006-07-08 on debian, modified by Debian
 (Debian emacs-snapshot package, version 1:20060707-1)
X server distributor `The X.Org Foundation', version 11.0.70000000
configured using `configure '--build' 'i486-linux-gnu' '--host' 'i486-linux-gnu' '--prefix=/usr' '--sharedstatedir=/var/lib' '--libexecdir=/usr/lib' 
'--localstatedir=/var' '--infodir=/usr/share/info' '--mandir=/usr/share/man' '--with-pop=yes' 
'--enable-locallisppath=/etc/emacs-snapshot:/etc/emacs:/usr/local/share/emacs/22.0.50/site-lisp:/usr/local/share/emacs/site-lisp:/usr/share/emacs/22.0.50/site-lisp:/usr/share/emacs/site-lisp:/usr/share/emacs/22.0.50/leim' 
'--with-x=yes' '--with-x-toolkit=athena' '--with-toolkit-scroll-bars' 'CFLAGS=-DDEBIAN -g -O2' 'build_alias=i486-linux-gnu' 'host_alias=i486-linux-gnu''

Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: C
  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: de_DE.UTF-8
  locale-coding-system: utf-8
  default-enable-multibyte-characters: t

Major mode: Dired by name

Minor modes in effect:
  display-time-mode: t
  auto-image-file-mode: t
  show-paren-mode: t
  tooltip-mode: t
  mouse-wheel-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  auto-compression-mode: t
  temp-buffer-resize-mode: t
  column-number-mode: t
  line-number-mode: t
  transient-mark-mode: t

Recent input:
<return> C-x k <return> g U g C-x 1 <up> <up> <up>
<escape> ! t o u c h SPC g c . h t m l , g z <backspace>
<backspace> <backspace> , <backspace> . g z <return>
g <down> <down> <down> <down> <down> <down> <down>
<down> <down> <down> Z y <escape> ! <up> <right> <right>
<right> <right> <right> <right> <right> <right> <right>
<right> <right> <right> <right> <right> <right> <right>
<backspace> <backspace> <backspace> <return> g Z y
<up> D y e s <return> g Z y g M-x r e p o r t - e m
<tab> <return>

Recent messages:
Uncompressing /usbstick/gc.html.gz...
gunzip ("/usbstick/gc.html.gz")
gunzip: /usbstick/gc.html already exists;       not overwritten
Failed to compress/usbstick/gc.html.gz
1 of 1 deletions
1 deletion done
Compress or uncompress gc.html.gz? (y or n)
Uncompressing /usbstick/gc.html.gz...done
Compress or uncompress: 1 file.
Loading emacsbug...done