Emacs refusing to switch to iso-latin-1

["Sébastien Vauban" <zthjwsqqafhv@spammotel.com>]

Hi,

For a couple of weeks, I've chosen to select utf-8 as my default
coding system. For the sake of facility, I resisted for years,
but I'd have to adapt sooner or later, so...

--8<---------------cut here---------------start------------->8---
;; system locale to use for formatting time values
(setq system-time-locale "en_US.utf8")

;; default coding system (for new files)
(prefer-coding-system 'utf-8)

;; to copy and paste to and from Emacs through the clipboard
(set-selection-coding-system 'utf-8)
--8<---------------cut here---------------end--------------->8---

Doing so, my Important settings are now:

--8<---------------cut here---------------start------------->8---
  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: en_US.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: utf-8-unix
  default-enable-multibyte-characters: t
--8<---------------cut here---------------end--------------->8---

My problem is that, when creating of updating files for some
applications, I sometimes have to output pure iso-latin-1...

I did create a new file, from a scratch buffer. It was thus
considered as utf-8 format.

I told emacs to save the file in iso-latin-1-unix, with `C-x
<RET> f iso-latin-1-unix'.

    Note - BTW, it'd be better if it was called `C-x <RET> s'
    (for saving), like `C-x <RET> r' is used for revert.

I see:

    o   the coding system flag changing from `U' to `1', and
    o   the modified flag from `--' to `**'.

Excellent...

But, when I do my `C-x C-s', just after it's done, it see back
`-U:--' in my modeline.

Checking with `C-u C-x =' or with `hexl-mode', I see that the
file is still in utf-8; its size did not change neither...

So, I can't save in iso-latin-1...

I could reproduce it both under Windows and under Linux. And it
"works" that way 100% of the times.

Thanks for your help!!

Best regards,
  Seb

-- 
Sébastien Vauban