bug#20663: page.el (forward-page): Avoid skipping pages

[Eli Zaretskii]

> From: Marcin Borkowski <mbork@mbork.pl>
> Cc: Eli Zaretskii <eliz@gnu.org>,  20663@debbugs.gnu.org
> Date: Mon, 11 Apr 2016 12:20:07 +0200
> 
> I spent a few minutes on this with Edebug and Git today.

Thanks.

> > - All the patch does it make the code consistent with its comments, that is:
> >
> >     ;; In case the page-delimiter matches the null string,
> >     ;; don't find a match without moving.
> 
> Seems ok.
> 
> > - If you try the recipe (I just did on Emacs 24.5.1, don't have time to 
> > check
> > now on upstream), you'll see that a page gets skipped, which is not the 
> > desired
> > behaviour.
> 
> Condirmed.  And it doesn't happen with the patch installed.

Can one of you please explain why the original code misbehaves?

> For instance, when the point is -!-, is the point on the first or
> second page here?  Emacs with and without the patch has different
> opinions on that.

Good point.