Changes 8.4.2:
* Protect against indirect security threats caused by index functions
  changing session-local state
* Reject SSL certificates containing an embedded null byte in the
  common name (CN) field
* Fix hash index corruption
* Fix possible crash during backend-startup-time cache initialization
* Avoid crash on empty thesaurus dictionary
* Prevent signals from interrupting VACUUM at unsafe times
* Fix possible crash due to integer overflow in hash table size
  calculation
* Fix crash if a DROP is attempted on an internally-dependent object
* Fix very rare crash in inet/cidr comparisons
* Ensure that shared tuple-level locks held by prepared transactions
  are not ignored
* Fix premature drop of temporary files used for a cursor that is
  accessed within a subtransaction
* Fix memory leak in syslogger process when rotating to a new CSV
  logfile
* Fix memory leak in postmaster when re-parsing "pg_hba.conf"
* Fix Windows permission-downgrade logic
* Make FOR UPDATE/SHARE in the primary query not propagate into WITH
  queries
* Fix bug with a WITH RECURSIVE query immediately inside another one
* Fix concurrency bug in hash indexes
* Fix incorrect logic for GiST index page splits, when the split
  depends on a non-first column of the index
* Fix wrong search results for a multi-column GIN index with
  fastupdate enabled
* More...

(adam)