* debian/patches:
+ Update upstream/228671-pipe-mime.patch: Fix segfaults with ssh tunnels.
Thanks Nikolaus Schulz (Closes: #569279)
+ + Update upstream/528233-readonly-open.patch: Only chmod saved
+ attachments, not existing files. (Closes: #572203)
+ Add upstream/573823-imap_internal_date: Set internaldate of messages
appended to IMAP mailboxes (Closes: #573823)