Log Message:
Changes 8.4.7:
* Avoid failures when "EXPLAIN" tries to display a simple-form CASE
  expression.
* Fix assignment to an array slice that is before the existing range
  of subscripts.
* Avoid unexpected conversion overflow in planner for very distant
  date values.
* Fix pg_restore's text output for large objects (BLOBs) when
  standard_conforming_strings is on.
* Fix erroneous parsing of tsquery values containing ... &
  !(subexpression) | ...
* Fix buffer overrun in "contrib/intarray"'s input function for the
  query_int type.
* Fix bug in "contrib/seg"'s GiST picksplit algorithm.