bug#29422: 27.0.50; Symbol enable-multibyte-characters may not be buffer-local

[Eli Zaretskii]

> From: Stefan Monnier <monnier@iro.umontreal.ca>
> Cc: michael_heerdegen@web.de,  29422@debbugs.gnu.org
> Date: Sat, 25 Nov 2017 21:07:22 -0500
> 
> My patch did not touch `setq`.  It just made `make-local-variable` and
> `make-buffer-local-variable` signal the same error as `setq`.
> 
> > I meant for you to do that, as part of fixing this problem, but if you
> > don't feel like it, we should at least change the ELisp manual, as it
> > now contradicts the code.
> 
> If you mean the doc of `setq`, then I guess this discrepancy has been
> with us since Emacs-21.

Not unheard of, and not a good reason to leave it that way.