bug#64391: buffer narrowing slowdown regression in emacs 29

[Eli Zaretskii]

> Date: Sun, 09 Jul 2023 18:03:02 +0000
> From: Gregory Heytings <gregory@heytings.org>
> cc: acohen@ust.hk, 64391@debbugs.gnu.org, mattias.engdegard@gmail.com, 
>     monnier@iro.umontreal.ca, bugs@gnus.org
> 
> >> +When the optional argument @var{label}, which is evaluated to get the
> >> +label to use and must not be @code{nil},
> >
> > What "must not be nil": the label or the result of its evaluation?
> >
> 
> The result of the evaluation of the label argument.  I don't know how to 
> make this clearer.

Instead of "must not be nil", say "must not yield nil".