bug#3210: face customization fails after set-face-attribute

[Chong Yidong]

David Reitter <david.reitter@gmail.com> writes:

> (set-face-attribute 'default nil
>                   :height 130
>                   :family "Lucida Grande")
> ;; modifies default face
>
> (customize-face 'default)
> ;; switch back manually to Monaco and "set for current session"
>
> (make-frame-command)  ;; C-x 5 2
> ;; the new frame is shown in Lucida.  Why?

I have edited the docstring of set-face-attribute, to make it clearer
that this function overrides face specs.