bug#23814: 24.5; bug of hz coding-system

[Eli Zaretskii]

> > From: ynyaaa@gmail.com
> Cc: 23814@debbugs.gnu.org
> Date: Wed, 22 Jun 2016 22:47:00 +0900
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> > This is by design, and mentioned in the doc string of that
> > coding-system.  Since Emacs is Unicode based, the _only_ way of having
> > "chinese-gb2312 characters" is by using that text property.
> 
> `encode-hz-region' uses `iso-2022-7bit' coding-system internally,
> replacing it with the coding-system below will work.
> 
> (define-coding-system 'iso-2022-cn-gb
>   "ISO 2022 based 7bit encoding only for Chinese GB2312."
>   :coding-type 'iso-2022
>   :mnemonic ?C
>   :charset-list '(ascii chinese-gb2312)
>   :designation [(ascii chinese-gb2312) nil nil nil]
>   :flags '(ascii-at-eol ascii-at-cntl designation 7-bit safe)
>   )

What advantages does this change have?