Too Late in Fixing Continuation Lines?

[kousik]

Suppose we have a subject which has a newline, and next line doesn't
start with a space. message-check-news-header-syntax() offers to fix
such a broken subject by inserting a space in front of the second
line. But if we have gnus-posting-style to insert a new header, then
message-goto-eoh() will not be able to see the broken subject line,
inserting the new header there itself. Example:

(1) Original message:
---------------------
Subject: Hello
World

(2a) Fixed by message-check-news-header-syntax() (no extra header):
--------------------
Subject: Hello
 World

(2b) gnus-posting-style inserting a header:
-------------------
Subject: Hello
X-New-Header: foobar
World

(3) "Fixed" by message-check-news-header-syntax()
------------------------
Subject: Hello
X-New-Header: foobar
 World

So you can see now `World' became part of X-New-Header!

I don't know enough lisp & gnus codebase to fix it, I hope someone
here will have enough clues.

regards
Kousik