bug#49797: 28.0.50; Setting face to custom fontset doesn't work

[Eli Zaretskii]

> From: Yuan Fu <casouri@gmail.com>
> Date: Sun, 1 Aug 2021 12:27:32 -0400
> Cc: Kenichi Handa <handa@gnu.org>,
>  49797@debbugs.gnu.org
> 
> >> The documentation of face attributes doesn't mention it for some reason
> > 
> > Yes, it does: see the doc string of set-face-font.
> 
> I mean the :fontset attribute. Maybe it is supposed to be merged into the 
> :font attribute so documentations don’t mention :fontset? But the code still 
> refers to it (Finternal_set_lisp_face_attribute).

I think the :fontset attribute isn't supposed to be set by Lisp
programs.  It's for internal use.