We need every instruction to have its own arena, because we want to
  track instruction's state (INITIALIZED_FOR_SP -> EXECUTED). Because of 
  `if' statements and other conditional instructions used in stored 
  procedures, not every instruction of a stored procedure gets executed 
  during the first (or even subsequent) execution of the procedure. 
  So it's better if we track the execution state of every instruction 
  independently.
  All instructions of a given procedure now also share sp_head's 
  mem_root, but keep their own free_list.
  This simplifies juggling with free Item lists in sp_head::execute.
- free_items() moved to be a member of Query_arena. 
- logic of 'backup_arena' debug member of Query_arena has been
  changed to support
  multi-backups. Until now, TRUE 'backup_arena' meant that there is
  exactly one active backup of the THD arena. Now it means simply that
  the arena is used for backup, so that we can't accidentally overwrite an 
  existing backup. This allows doing multiple backups, e.g. in
  sp_head::execute and Cursor::fetch, when THD arena is already backed up
  but we want to set yet another arena (usually the 'permanent' arena,
  to save permanent transformations/optimizations of a parsed tree).

into mysql.com:/home/svoj/devel/mysql/mysql-5.0.9

into rurik.mysql.com:/home/igor/mysql-5.0

  Identation correction.

into mysql.com:/space/my/mysql-5.0-build

into rurik.mysql.com:/home/igor/dev/mysql-5.0-0

into mysql.com:/home/psergey/mysql-5.0-back-vac-look

Fix for "multiple definition of __cxa_pure_virtual" link failure
when compiling with icc.

into mysql.com:/space/my/mysql-5.0.8-clone

  Fixed buf #11487.
  Added a call of  QUICK_RANGE_SELECT::init to the
  QUICK_RANGE_SELECT::reset method. Without it the second
  evaluation of a subquery employing the range access failed.
subselect.result, subselect.test:
  Added a test case for bug #11487.

into mdk10.(none):/home/reggie/bk/mysql-5.0-base

into moonbone.local:/work/mysql-5.0-merge

  Fix for bugfix #9728 merge

into radha.local:/Volumes/disk2s1/mysql-5.0

into mdk10.(none):/home/reggie/bk/bug9148

into moonbone.local:/work/mysql-4.1-bug-8147

  Fix for fix for bug#9728 decreased functionality in "on duplicate key update"
  Have to return false to set flag for whole expression.

into radha.local:/Volumes/disk2s1/mysql-5.0

  Add a slave when running the federated test case

into  mysql.com:/Users/emurphy/src/bk-clean/mysql-5.0

into  mysql.com:/Users/emurphy/src/bk-clean/mysql-5.0

  Bug#11481, set charset directory to mysqlbinlog

into  mysql.com:/Users/emurphy/src/bk-clean/mysql-5.0

into mysql.com:/Users/kent/mysql/bk/mysql-5.0

into  mysql.com:/Users/emurphy/src/bk-clean/mysql-5.0

into mysql.com:/home/psergey/mysql-5.0-bug8441

into  mysql.com:/Users/emurphy/src/bk-clean/mysql-5.0

into mysql.com:/home/psergey/mysql-5.0-bug8441

into mysql.com:/mnt/archive/svoj/mysql/mysql-5.0

into hundin.mysql.fi:/home/marko/mysql-5.0-current

into mysql.com:/opt/local/work/mysql-5.0-10736-new

into mysql.com:/space/my/mysql-4.1

into mysql.com:/home/svoj/devel/mysql/yassl-mysql-5.0