bug#57531: 28.1; Character encoding missing for "eo"

[Gregory Heytings]

> > > (locale-info 'codeset)
> >
> > If you mean that set-locale-environment should use that, please say 
> > that explicitly.  And then feel free to suggest a patch that does TRT 
> > with all the convoluted logic and preferences there, so that we don't 
> > disrupt the setup it took us decades to come up to, for the benefit of 
> > a single obscure locale.
>
> It's not for a single obscure locale, it's for all of them.

Except that most other locales have "UTF-8" in their name when UTF-8 
should be used, so the current logic selects the right encoding, without 
consulting (locale-info 'codeset).  For example, with the locale "mt_MT", 
Emacs uses ISO-8859-3, and with the locale "mt_MT.UTF-8", Emacs uses 
UTF-8.