bug#66006: 30.0.50; (setf (buffer-string) "text") doesn't respect narrowing

[Eli Zaretskii]

> From: Sebastián Monía <code@sebasmonia.com>
> Date: Fri, 15 Sep 2023 10:35:41 -0600
> 
> 
> (buffer-string) behaves different in a call vs setf-ing.
> In the former case, it respects narrowing, but when using setf, it
> replaces the entire buffer. To be honest, I don't know if it should set
> only the narrowed region (from a correctness point of view, maybe it is
> expected for setf to do the whole thing). But if it won't, the
> difference in behaviour should probably be documented.

Adding Stefan.