bug#65468: 29.1; describe-theme fails to describe some themes not loaded

[Eli Zaretskii]

> Cc: 65468@debbugs.gnu.org
> Date: Wed, 23 Aug 2023 06:53:03 -0300
> From: Mauro Aranda <maurooaranda@gmail.com>
> 
> Thierry Volpiatto <thievol@posteo.net> writes:
> 
>  > This because `describe-theme-1` is not looping in buffer to find
>  > `deftheme` definition.
> 
> It is a convention that the first form should be a call to deftheme.
> But it seems built-in themes have deviated from that convention.  And
> other themes might as well, I don't know.
> 
>  >
>  > Try (describe-theme 'leuven) to reproduce (if not already loaded of 
> course).
>  >
> 
> At least for the leuven themes, it should be easy to make them follow
> the convention.

I think we should indeed fix the themes that come with Emacs.