mail-header-separator starting with whitespace fails

[Russ Allbery <eagle@eyrie.org>]

Hello all,

I just upgraded to Emacs 24 from Emacs 23, with the corresponding change
in Gnus versions.  For the most part this went smoothly (thank you!).  But
there was one rather annoying hiccup that caused some problems, and I
thought I'd mention it somewhere so that people could consider whether
it's worth fixing.

I've never liked the default mail-header-separator in Emacs.  I think it
blends in with the header and the start of the body text.  So for years
I've used:

    (setq mail-header-separator (concat (make-string 39 ? ) "."))

to create a separator that's much less obtrusive.

Unfortunately, when upgrading from Emacs 23 to Emacs 24, something in Gnus
or in the underneath modes changed so that this mail-header-separator no
longer works.  It's appended to the Content-Type header (causing message
corruption if it has a charset setting), and then the first line of the
body is lifted into the headers and disappears.

Removing this setting fixes the problem, but brings back the default
message separator.

I did a little bit of poking around, and it looks like something inside
the Gnus message code isn't actually using mail-header-separator but
instead is looking for the first line in the buffer that doesn't look like
a header.  Since my message separator looked like a continuation line, it
skipped right past it and kept going.  This seems surprising to me.  I
think whatever is in mail-header-separator should always work, even if it
looks like a header.

-- 
Russ Allbery (eagle@eyrie.org)              <http://www.eyrie.org/~eagle/>