Log Message:
Changelog v0.4.2:
* Incompatible change in Sieve doveadm plugin: the root attribute for
  Sieve scripts is changed. Make sure that you update both sides of a
  dsync setup simultaneously when Sieve is involved, otherwise
  synchronization will likely fail.
+ Added support for sending Sieve vacation replies with an actual
  sender, rather than the default <> sender. Check the updated
  doc/extensions/vacation.txt for more information.
- Fixed a binary code read problem in the `set' command of the Sieve
  variables extension. Using the set command with a modifier and an
  empty string value would cause code corruption problems while running
  the script.
- Various fixes for doveadm-sieve plugin, mostly crashes. These include
  a fix for the `Invalid value for default sieve attribute' problem.
- Various fixes for compiler and static analyzer warnings, e.g. as
  reported by CLang and on 32 bit systems.
- Fixed the implementation of the new :options flag for the Sieve
  include extension.
- Fixed potential segfault bug at deinitialization of the lda-sieve
  plugin.
- Fixed messed up hex output for sieve-dump tool.