bug#24644: 26.0.50; Emacs 25: set-fontset-font does not take effect with some ASCII symbols

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 08 Oct 2016 23:15:06 +0900
> From: Toshikazu Nakamura <bmcbq234@yahoo.co.jp>
> 
> I use Emacs for editing texts that contain Japanese as well as English
> and other languages. In order to give characters of each language a
> better appearance, I use a fontset that specifies a different font for
> ASCII characters and double-width Japanese characters.
> 
> Since Emacs 25.1, however, I find that the default ASCII font is
> always used for some characters that belongs to some other character
> set (e.g. japanese-jisx0208) and for which another font is specified.

This is a deliberate change in Emacs 25.1.  Preferring the default
face's font is better in the vast majority of cases, because it
doesn't disrupt the text alignment.  The preferred charset shown by
"C-u C-x =" has nothing to do with selecting the font.  (I also wonder
what does a character such as u+2026 has to do with Japanese
characters.)

I've now added a variable that you can set to disable the new behavior
and get back the old pre-Emacs 25.1 behavior, for those users who
want/need that.  The change is on the emacs-25 branch, so Emacs 25.2
will have it.

With that, I'm marking this bug done.

Thanks.