bug#34898: 24.4; `message-separator' face only works for default value of `mail-header-separator'

[Eric Abrahamsen <eric@ericabrahamsen.net>]

Emanuel Berg <moasenwood@zoho.eu> writes:

> On gmane.emacs.help, Sun, 17 Mar 2019 15:22:50 +0100,
> Damien Collard wrote in Emanuel Berg's thread
> "what has the face `message-separator' *really*
> done for us?"
>
>     Well, it seems to only be of effect when
>     `mail-header-separator' has its default
>     value "--text follows this line--".
>     I checked, and
>
>     - when it's the default separator, I can
>     confirm that changing the face
>     `message-separator' does change the
>     separator's color.
>
>     - when I changed `mail-header-separator' to
>     "---" (or anything different from the
>     default), the face `message-separator'
>     doesn't apply to it anymore!
>
>     So it's a bug.

The value of `mail-header-separator' gets added to
`message-font-lock-keywords', which does the actual fontification. Using
setq to change the value of `mail-header-separator' did not change the
font lock keyword, despite setting the variable before message.el is
loaded (or is it pre-loaded?). Using the customize interface to set
`mail-header-separator' *does* work as expected.

Dunno if it's supposed to work this way or not.

Eric