Problem writing backupfile in a protected directory

[Christoph Conrad]

Saving a modified file i am allowed to access (owner) in a directory i
am not allowed to write in (no new files allowed). Emacs seems to hang,
but quitting works, and with debug-on-quit t:

Debugger entered--Lisp error: (quit)
  copy-file("/etc/apt/sources.list" "/etc/apt/sources.list~" t t excl)
  byte-code("ÂÃďˆÅ    ƉÇ%ˆÂ‡" [from-name to-name nil (delete-file to-name) 
((file-error)) copy-file t excl] 6)
  backup-buffer-copy("/etc/apt/sources.list" "/etc/apt/sources.list~" 420)
  byte-code("„c       
„c\nƒÆÇ\nÈ\"W„cÉÊ!!ƒc\fƒ)Ë!ÌV„c„3šƒmÍ!„TÎ8š…_š…_Î8X…
_Ï8†_Ð!?)ƒmÑ\n#ˆ‚zÒÓ#ˆ\nBƇ" [file-precious-flag 
backup-by-copying modes real-file-name backup-by-copying-when-linked 
backup-by-copying-when-mismatch 0 logand 3072 file-writable-p 
file-name-directory file-nlinks 1 file-attributes 2 9 
file-ownership-preserved-p backup-buffer-copy rename-file t 
backup-by-copying-when-privileged-mismatch attr backupname setmodes] 4)
  byte-code("…       Æ=„   Ç=…   †ÈÉÊ\n\"!Ë!ÇÌ͏ˆÆ 
ƒ:ƒ:ÇÎϏˆA‰„.*‡" [targets delete-old-versions real-file-name 
buffer-file-name modes buffer-backed-up t nil y-or-n-p format "Delete excess 
backup versions of %s? " file-modes (byte-code "„c  
„c\nƒÆÇ\nÈ\"W„cÉÊ!!ƒc\fƒ)Ë!ÌV„c„3šƒmÍ!„TÎ8š…_š…_Î8X…
_Ï8†_Ð!?)ƒmÑ\n#ˆ‚zÒÓ#ˆ\nBƇ" [file-precious-flag 
backup-by-copying modes real-file-name backup-by-copying-when-linked 
backup-by-copying-when-mismatch 0 logand 3072 file-writable-p 
file-name-directory file-nlinks 1 file-attributes 2 9 
file-ownership-preserved-p backup-buffer-copy rename-file t 
backup-by-copying-when-privileged-mismatch attr backupname setmodes] 4) 
((file-error ...)) (byte-code "address@hidden" [targets delete-file] 2) 
((file-error)) setmodes] 5)
  backup-buffer()
  basic-save-buffer-2()
  basic-save-buffer-1()
  basic-save-buffer()
  save-buffer(1)
  call-interactively(save-buffer)

So it can't write a backupfile, that's correct. It should detect this
and not write a backupfile, issueing a warning. I remember that this at
least some months ago this was the behaviour i was accustomed.

In GNU Emacs 22.0.50.1 (i686-pc-linux-gnu)
 of 2005-06-01 on brabbelbox
Distributor `The XFree86 Project, Inc', version 11.0.40300001
configured using `configure  'CC=ccache gcc''

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: address@hidden
  locale-coding-system: iso-8859-15
  default-enable-multibyte-characters: t

Major mode: Default-Major

Minor modes in effect:
  partial-completion-mode: t
  recentf-mode: t
  minibuffer-electric-default-mode: t
  auto-image-file-mode: t
  erc-button-mode: t
  erc-ring-mode: t
  erc-pcomplete-mode: t
  erc-track-mode: t
  erc-fill-mode: t
  delete-selection-mode: t
  pc-selection-mode: t
  show-paren-mode: t
  icomplete-mode: t
  mouse-wheel-mode: t
  tooltip-mode: t
  auto-compression-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  unify-8859-on-decoding-mode: t
  unify-8859-on-encoding-mode: t
  utf-translate-cjk-mode: t
  line-number-mode: t
  transient-mark-mode: t
  next-error-follow-minor-mode:  Fol
  abbrev-mode: t

Recent input:
i t SPC t ) <return> C-x C-f <up> <return> # M-s q 
M-s <right> <right> <right> <right> H-a <home> <left> 
<left> <left> <home> <left> <C-home> <S-down> <S-down> 
<S-down> <S-down> <S-down> <S-down> <S-down> <S-down> 
<S-down> <S-down> <S-down> <S-down> <C-insert> <C-M-up> 
<C-M-up> q C-_ C-_ <M-delete> <M-delete> <C-backspace> 
C-x C-f <backspace> <backspace> <backspace> <backspace> 
<backspace> <backspace> <backspace> o e l <tab> e t 
<tab> P R <tab> <return> C-s c o p y - b <C-home> <M-delete> 
M-x b a c k <tab> u <tab> <backspace> <backspace> <backspace> 
<backspace> <backspace> r e p o r t - e m <tab> <r
eturn>

Recent messages:
Mark set
Back to top level.
Undo! [2 times]
Updating buffer list...done
Commands: m, u, t, RET, g, k, S, D, Q; q to quit; h for help
Note: file is write protected
Mark set
Mark saved where search started
Making completion list...
Loading emacsbug...done