bug#69739: 30.0.50; `type-of` is not precise enough

[Rudolf Schlatte]

Stefan Monnier via "Bug reports for GNU Emacs, the Swiss army knife of
text editors" <bug-gnu-emacs@gnu.org> writes:

>  * Incompatible Changes in Emacs 30.1
>  
> +** 'type-of' sometimes returns more precise types.
> +More specifically, for nil and t it returns 'null' and 'boolean'
> +instead of just 'symbol' and for "subrs", it now returns one of
> +'special-form', 'subr-primitive', or 'subr-native-elisp'.

Is it true that in all cases, if `(type-of x)' used to return `foo'
before the change, `(typep x 'foo)' still returns t after the change?
If so, that might be worth mentioning, since it makes fixing broken code
easier.