bug#62815: Gnus: MIME types of attachments contain regexp quotation

[Eli Zaretskii]

> Cc: 62815@debbugs.gnu.org
> Date: Thu, 13 Apr 2023 17:48:22 +0300
> From: Eli Zaretskii <eliz@gnu.org>
> 
> > From: Torsten Bronger <bronger@physik.rwth-aachen.de>
> > Date: Thu, 13 Apr 2023 13:46:38 +0200
> > 
> > Hallöchen!
> > 
> > Since commit 3faa508eba84a1983732099cbd3cc1eaad404158, I observe
> > incorrect MIME types in my outgoing mails, e.g.
> > 
> > …
> > --=-=-=
> > Content-Type: application/vnd\.oasis\.opendocument\.spreadsheet
> > Content-Disposition: attachment;
> >  filename=2022-12-15_Nachbestellung_Studio.ods
> > Content-Transfer-Encoding: base64
> > …
> > 
> > 
> > Reason is that when attaching a file to a mail in Gnus, the MIME
> > type is suggested by Gnus, and this suggestion contains the
> > incorrect backslashes.
> 
> Lars, could you please look into this?

Ping!

Andrew, perhaps you could look into this some time soon?  It sounds
like a recent regression, so I'd like to fix this in Emacs 29.