bug#36167: [PATCH] Replace manually crafted hex regexes with [[:xdigit:]]

[Eli Zaretskii]

> Cc: mattiase@acm.org, 36167@debbugs.gnu.org, hi-angel@yandex.ru
> From: Paul Eggert <eggert@cs.ucla.edu>
> Date: Tue, 11 Jun 2019 10:18:44 -0700
> 
> On 6/11/19 10:04 AM, Eli Zaretskii wrote:
> > Where did the question about non-ASCII
> > digits come from, given this text?
> 
> It came from POSIX, where [:xdigit:] and [:digit:] might match other 
> characters.

Yes, but when using Emacs and coding for Emacs, one must read the
Emacs documentation, which clearly says what these do in Emacs.