Log Message:
dovecot2-pigeonhole: updated to 0.5.3

Changelog v0.5.3:
- Fix assertion panic occurring when managesieve service fails to open
  INBOX while saving a Sieve script. This was caused by a lack of
  cleanup after failure.
- Fix specific messages causing an assert panic with actions that
  compose a reply (e.g. vacation). With some rather weird input from the
  original message, the header folding algorithm (as used for composing
  the References header for the reply) got confused, causing the panic.
- IMAP FILTER=SIEVE capability: Fix FILTER SIEVE SCRIPT command parsing.
  After finishing reading the Sieve script, the command parsing
  sometimes didn't continue with the search arguments. This is a time-
  critical bug that likely only occurs when the Sieve script is sent in
  the next TCP frame.