Log Message:
Update dovecot2-pigeonhole to 0.4.5.

Changelog v0.4.5:

+ Added a Pigeonhole version banner to doveconf output. This way, future
  bug reports will also include Pigeonhole version information.
- Fixed handling of implicit keep. Last version erroneously reported
  that implicit keep succeeded after an earlier failure, while it in
  fact had failed. Particularly occurred for mailbox quota errors.
- Fixed segfault occurring on SunOS systems when there is no active
  script.

Changelog v0.4.4:

* Added support for Japanese mail addresses with dots at non-standard
  places in localpart.
* Changed handling of ENOSPACE into a normal temporary failure and added
  handling of ENOQUOTA as a user error.
* Restructured result execution, so that all actions which involve mail
  storage are always committed before all others.
+ Implemented support for generic Sieve storages. Using alternative
  storages now also possible for sieve_before/sieve_after.
+ Implemented storage driver for retrieving Sieve scripts from LDAP.
  This currently cannot be used with ManageSieve.
+ Implemented sieve_redirect_envelope_from setting, which allows
  configuring the envelope sender of redirected messages.
- Fixed handling of mail storage errors occurring while evaluating the
  input message.
- managesieve-login:
   - Removed bogus ALERT response code returned for AUTHENTICATE
     command.
   - Fixed handling of invalid initial response argument to AUTHENTICATE
     command.
- Fixed handling of stream errors in lexical scanner.
- Fixed handling of SMTP errors. Permanent and temporary errors were
  mixed up.
- Fixed several problems reported by CLang 3.4.
- duplicate extension: Fixed erroneous compile error about conflicting
  tags when `:handle' argument was used last.
- relational extension: Fixed error handling of `:value' match.
- editheader extension: Fixed header unfolding and header iteration.
- mailbox extension: Fixed the `:create' tag, which erroneously
  subscribed an existing folder.
- extprograms plugin: Fixed handling of error codes.
- doveadm-sieve plugin: Fixed several bugs. Synchronization of symbolic
  link in the file storage should now also work properly.