Log Message:
dovecot2-pigeonhole: updated to 0.5.17

0.5.17:
- duplicate: The Sieve duplicate test is prone to false negatives when
  the user receives many e-mails concurrently, meaning that duplicate
  deliveries can still occur.
- fileinto: v2.3.16 regression: Sieve delivery crashes if mail is
  delivered to non-existing and existing folder.
- imap-filter-sieve: v2.3.15 regression: The CPU limits on Sieve
  execution are too easily exceeded in IMAP context (the IMAPSieve and
  FILTER=SIEVE capabilities). Changed the default to unlimited CPU time
  for IMAP context, since similar excessive resource usage can be caused
  by other means as well. The CPU limits on Sieve scripts executed at
  LDA/LMTP delivery are still enforced by default.
- redirect:  The Sieve redirect action has protections against users
  triggering mail loops. Unfortunately, the detection of a redirect mail
  loop sometimes causes the message to get lost if no other Sieve action
  is applied that delivers the message somewhere else.
- redirect: v2.3.16 regression: With certain Sieve scripts if redirect
  fails due to temporary failure, the lmtp process may crash after the
  delivery. Fixes:
  Panic: file mail-user.c: line 229 (mail_user_deinit):
  assertion failed: ((*user)->refcount == 1).