tar-mode shouldn't use write-contents-functions

[Stefan Monnier <monnier@iro.umontreal.ca>]

Could you explain your latest change to tar-mode:

   ;;; tar-mode.el --- simple editing of tar files from GNU emacs
   ----------------------------
   revision 1.133
   date: 2008-12-31 04:58:53 -0500;  author: schwab;  state: Exp;  lines: +13 -10;  commitid: bktiZYl153iysBwt;
   (tar-mode): Set write-contents-functions instead of
   write-region-annotate-functions.
   (tar-mode-write-contents): New function.
   (tar-write-region-annotate): Remove.
   ----------------------------

This seems to basically undo my earlier change:

   revision 1.128
   date: 2008-05-28 13:43:58 -0400;  author: monnier;  state: Exp;  lines: +15 -22;  commitid: vJEploj5uzkA0L4t;
   (tar-summarize-buffer): Fix reporter initialization.
   (tar-mode): Use write-region-annotate-functions rather than
   write-contents-functions.
   (tar-extract): Remove unused var `pos'.
   (tar-subfile-save-buffer): Remove unused var `following-descs'.
   (tar-mode-write-file): Remove.
   (tar-write-region-annotate): New function.
   ----------------------------

Could you explain the reason for it?  IIUC your change causes (among
other things) auto-save to fail (it saves the summary rather than the
raw tar data).


        Stefan