bug#49558: fill paragraph in texinfo-mode fails with @

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: larsi@gnus.org,  lisa-asket@perso.be,  49558@debbugs.gnu.org
> Date: Wed, 14 Jul 2021 09:49:27 -0400
> 
> >> In which sense do our default values not heed this rule?
> > The same line could match both paragraph-start and paragraph-separate.
> 
> But that rule doesn't say they can't, it just implies that if a line
> matches both then it will be treated as a paragraph separator:
> 
>     Lines that start a new paragraph and are contained in it must
>     match only ‘paragraph-start’, not ‘paragraph-separate’. 

That's not my reading of that text, so I guess it should be reworded
(to avoid the implied double negation).