bug#8308: 23.3; Use utf-8 for writing abbrev file

[Stefan Monnier]

> Is it OK to change the encoding for abbrev file to utf-8?
> === modified file 'lisp/abbrev.el'
> --- a/lisp/abbrev.el  2011-03-21 05:49:12 +0000
> +++ b/lisp/abbrev.el  2011-03-21 06:20:36 +0000
> @@ -225,9 +225,9 @@
>                   abbrev-file-name)))
>    (or (and file (> (length file) 0))
>        (setq file abbrev-file-name))
> -  (let ((coding-system-for-write 'emacs-mule))
> +  (let ((coding-system-for-write 'utf-8))
>      (with-temp-file file
> -      (insert ";;-*-coding: emacs-mule;-*-\n")
> +      (insert ";;-*-coding: utf-8;-*-\n")
>        (dolist (table
>                 ;; We sort the table in order to ease the automatic
>                 ;; merging of different versions of the user's abbrevs

Sounds good in general, but I'm wondering whether we should worry about
the presence of abbrevs which include bytes (aka eight-bit-chars).
Using `utf-8-emacs' should fix those issues, but would then bump into
the problem that such abbrev files wouldn't be compatible with Emacs-22.


        Stefan