bug#45631: 27.1; regression: message-forward-ignored-headers no longer applies when forwarding as MIME

[Daniel Kahn Gillmor]

Hi Robert--

Thanks for taking a look into this!

On Tue 2021-01-05 14:06:54 +0100, Robert Pluim wrote:
> Iʼve compared emacs-26 and emacs-27, and the code is the same, which
> leads me to suspect something different in your
> configuration. 'message-forward-ignored-headers' is applied even when
> forwarding as MIME (despite the docstring)

hm, the docstring change was recent, apparently in response to #27715 :

https://git.savannah.gnu.org/cgit/emacs.git/commit/?id=57fbf0cf7bd4a85f2ad6f14aa92494545106b887

that's why i assumed there had been a change.

> except when 'message-forward-show-mml' is nil, or when itʼs 'best' and
> the forwarded message is either signed or encrypted.

Hm, i'm using 'best' for message-forward-show-mml (as the default) and
yes, it looks like the issue is that i just noticed it happening when
i went to forward a signed message.  Maybe it wasn't an issue before
because i wasn't forwarding a signed message?  I no longer have emacs
26.3 installed so i can't check that handily right now.

The message headers (outside of the cryptographic envelope) do *not*
affect the digital signature, so they ought to be safe to trim out
without invalidating the digital signature.  These are the message
headers that i want to trim.

> Or maybe youʼre forwarding from inside the *Article* buffer, I think
> Gnus behaves differently then.

I'm using notmuch-emacs, not gnus, but it reuses a lot of the existing
emacs MUA codebase, which is why i'm reporting it here.

Do you have a suggestion for how i can apply
message-forward-ignored-headers to a signed message?  I only want it to
apply to headers that aren't covered by the digital signature anyway.

      --dkg

signature.asc
Description: PGP signature