Just for the record, this bug was fixed in
http://git.savannah.gnu.org/cgit/emacs.git/commit/?id=4a5653cd2859308ada4bbf5ffc9fb9b283eef31a

And here's the bug report:
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=27504

On Mon, Jun 26, 2017 at 6:48 PM Michael Ax <michaelax@gmail.com> wrote:

> cool compromise; covers my use-cases. tks!
>
> But that would still allow the user to use setq to set that variable.
>
> True, but can we always prevent them from shooting themselves in the
> foot?
>
>
>
> --

Kaushal Modi