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

[Drew Adams]

> > +1.  At least the doc for [:digit:] should say exactly
> > what it matches.  Then it'll be clear for readers and
> > writers.
> 
> The last part says "the doc should say" as if the doc doesn't already
> say.

Yes, my bad. Forgot that it exists, and misread the
proposal as including its creation.