Non-MML forwarding strips Content-Transfer-Encoding

[Hrvoje Niksic <hniksic@xemacs.org>]

[ Please Cc the responses to me as I'm not on the list. ]

A bug in the forwarding code has just bit me.

I set `message-forward-show-mml' to nil because I prefer to forward
mails as they are.  Recently something broke, though.  If you set
`message-forward-show-mml' to nil and try to forward a message encoded
as base64 (e.g. one that contains only a picture), the
Content-Transfer-Encoding header gets stripped from the embedded
message.  You end up with a buffer that looks like this:

[#part type=message/rfc822 raw=t bla bla ...]
X-From-Line: ...
<correct MIME headers sans Content-Transfer-Encoding>

<... base64 body ...>
[#/part]

Obviously, stripping Content-Transfer-Encoding is wrong.  The
resulting message is corrupted because its body will be interpreted to
contain 7bit data.  It is also wrong in principle -- when
`message-forward-show-mml' is unset, I expect little or no tinkering
with the embedded message.  Gnus should just make sure it is correctly
embedded as a part, and the rest will follow from that.

The one place where Content-Transfer-Encoding is removed is in
message-forward-make-body.  I tried the obvious fix of removing
Content-Transfer-Encoding from message-forward-ignored-headers and
having message-forward-make-body manually remove
Content-Transfer-Encoding when message-forward-show-mml is t:

    --- message.el.orig	Tue Jul 23 15:30:29 2002
    +++ message.el	Tue Jul 23 15:32:22 2002
    @@ -336,3 +336,3 @@

    -(defcustom message-forward-ignored-headers "^Content-Transfer-Encoding:\\|^X-Gnus"
    +(defcustom message-forward-ignored-headers "^X-Gnus"
       "*All headers that match this regexp will be deleted when forwarding a message."
    @@ -5045,3 +5045,5 @@
                                (or (search-forward "\n\n" nil t) (point)))
    -	  (message-remove-header message-forward-ignored-headers t)))))
    +	  (message-remove-header message-forward-ignored-headers t)
    +	  (when message-forward-show-mml
    +	    (message-remove-header "^Content-Transfer-Encoding"))))))
       (message-position-point))

But even with this fix, something is *still* removing the
Content-Transfer-Encoding header.  `message-encode-message-body' and
`message-send-mail-partially' both do it, but I'm not sure how or
whether they get called.

Can someone please help?