misc/149633: Problem with replaying to PR

[Grzegorz Blach]

I think main problem is that Evolution and Claws-mail sent attachment in
RFC 2231 style,
and Roundcube sent its in compatible with RFC 2231 and 2047, but
unfortunately 
new version of roundcube seems code headers wrongly:

Headers from Roundcube 0.4 beta:
 Content-Transfer-Encoding: base64
 Content-Type: text/plain;
  name=firefox-sync.diff.txt;
  charset=UTF-8
 Content-Disposition: attachment;
  filename=firefox-sync.diff.txt


Older version of Rouncube (taken from PR/140877)
 Content-Transfer-Encoding: base64
 Content-Type: text/plain; charset=UTF-8;
  name=weave.diff.txt;
 Content-Disposition: attachment;
  filename=weave.diff.txt;