bug#38179: 26.1; clone-buffer globally unsets locally void variable

[Noam Postavsky]

There is no way to make a "locally void" variable.

> Let's create a test, which sets the default value of a variable but
> undefines it locally in some buffer.

>     (with-temp-buffer
>       (makunbound (make-local-variable var))

That will unbind the global value and local values, not just the local
one.