bug#37774: 27.0.50; new :extend attribute broke visuals of all themes and other packages

[Eli Zaretskii]

> Cc: 37774@debbugs.gnu.org, juri@linkov.net
> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Mon, 9 Dec 2019 16:07:54 +0200
> 
> > I guess you loaded the tests as a .el file?
> 
> Exactly. How else do you run the tests interactively?

  M-x load-file RET foo.elc RET
  M-x ert-run-tests-interactively RET RET

> > Why did you lose the sentence that starts with "By default"?
> 
> Because it's been untrue for some time. More faces than just region and 
> hl-line have this attribute set. I have put the (hopefully) full list in 
> NEWS now, but it's getting ridiculous. Certainly not something to 
> mention in the manual.

We could say something like "'region' and some others".  Not saying
that some have this by default would be a mistake, IMO.

> > Please keep the original wording by including "rather than inheriting
> > from it" in parentheses.
> 
> Like this?
> 
>    defface spec entirely (rather than inheriting from it), with the
>    exception of the :extend attribute (which is inherited).

Yes, thanks.