ange-ftp won't make remote backup files

[Chris Moore]

If I set ange-ftp-make-backup-files to t to get ange-ftp to make
backups before overwriting my 'precious data' then I get a backtrace
when I try to save a file remotely using ange-ftp.

The cause of the problem is that backup-buffer calls function
file-modes on the ange-ftp extended path name, which returns nil:

  Debugger entered--entering a function:
  * file-modes("/address@hidden:/marp/chris/test.txt")

  Debugger entered--returning value: nil
    file-modes("/address@hidden:/marp/chris/test.txt")

Here's the backtrace I get:

  Debugger entered--Lisp error: (wrong-type-argument number-or-marker-p nil)

    logand(nil 1023)

    backup-buffer-copy("/address@hidden:/marp/chris/test.txt" 
"/address@hidden:/marp/chris/Backup/test.txt.~2~" nil)

    (if (or file-precious-flag backup-by-copying (and modes ...) (and 
backup-by-copying-when-linked ...) (and ... ...)) (backup-buffer-copy 
real-file-name backupname modes) (rename-file real-file-name backupname t) 
(setq setmodes (cons modes backupname)))

    (condition-case nil (if (or file-precious-flag backup-by-copying ... ... 
...) (backup-buffer-copy real-file-name backupname modes) (rename-file 
real-file-name backupname t) (setq setmodes ...)) (file-error (setq backupname 
...) (message "Cannot write backup file; backing up in %s" ...) (sleep-for 1) 
(backup-buffer-copy real-file-name backupname modes)))

    (let ((delete-old-versions ...) (modes ...)) (condition-case nil (if ... 
... ... ...) (file-error ... ... ... ...)) (setq buffer-backed-up t) (if 
delete-old-versions (while targets ... ...)) setmodes)

    (condition-case nil (let (... ...) (condition-case nil ... ...) (setq 
buffer-backed-up t) (if delete-old-versions ...) setmodes) (file-error nil))

    (if backup-info (condition-case nil (let ... ... ... ... setmodes) 
(file-error nil)))

    (let ((real-file-name buffer-file-name) backup-info backupname targets 
setmodes) (setq real-file-name (file-chase-links real-file-name)) (setq 
backup-info (find-backup-file-name real-file-name) backupname (car backup-info) 
targets (cdr backup-info)) (if backup-info (condition-case nil ... ...)))

    (if (and make-backup-files (not backup-inhibited) (not buffer-backed-up) 
(file-exists-p buffer-file-name) (memq ... ...)) (let (... backup-info 
backupname targets setmodes) (setq real-file-name ...) (setq backup-info ... 
backupname ... targets ...) (if backup-info ...)))

    backup-buffer()

    basic-save-buffer-2()

    basic-save-buffer-1()

    basic-save-buffer()

    save-buffer(1)

  * call-interactively(save-buffer)

Chris.

In GNU Emacs 21.3.50.1 (i386-mingw-nt5.1.2600)
 of 2003-10-01 on CHRISLAP
configured using `configure --with-gcc (3.2)'

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: ENG
  locale-coding-system: iso-latin-1
  default-enable-multibyte-characters: t