execute crashes server": we were deleting lex->result
after each execute, but prepared statements assumed that
it's left intact.
The fix adds cleanup() method to select_result hierarchy,
so that result objects can be reused.
Plus we now need to delete result objects more wisely.

into serg.mylan:/usr/home/serg/Abk/mysql-4.1

in ha_commit_trans - why it didn't crash earlier ?

(cannot call it a "merge" :)

Abandoned improper use of MyISAM data.
Thanks Ingo!

into ice.snake.net:/Volumes/ice2/MySQL/bk/mysql-4.1

without InnoDB.

  Added test case for bug #4256.
join_outer.result:
  Fixed bug #4256.
item_cmpfunc.h:
  Fixed inconsistency of values of used_tables_cache and
  const_item_cache for Item_func_isnull objects.
  This inconsistency caused bug #4256.

into rurik.mysql.com:/home/igor/mysql-4.1

into ice.snake.net:/Volumes/ice2/MySQL/bk/mysql-4.1

into rurik.mysql.com:/home/igor/mysql-4.1

into mysql.com:/home/kostja/work/mysql-4.1-4912

 a second time". The bug was caused by incompatibility of
negations elimination algorithm and PS: during first statement 
execute a subtree with negation was replaced with equivalent 
subtree without NOTs.
The problem was that although this transformation was permanent, 
items of the new subtree were created in execute-local memory.
The patch adds means to check if it is the first execute of a
prepared statement, and if this is the case, to allocate items
in memory of the prepared statement.
The implementation:
- backports Item_arena from 5.0
- adds Item_arena::is_stmt_prepare(), 
  Item_arena::is_first_stmt_execute().
- deletes THD::allocate_temporary_pool_for_ps_preparing(),
  THD::free_temporary_pool_for_ps_preparing(); they
  were redundant.
and adds a few invariants:
- thd->free_list never contains junk (= freed items)
- thd->current_arena is never null. If there is no
  prepared statement, it points at the thd. 
The rest of the patch contains mainly mechanical changes and
cleanups.

  Fixed it to work, added function to fix include/mysql_version.h LICENSE tag from GPL to Commercial

into rurik.mysql.com:/home/igor/mysql-4.1

into serg.mylan:/usr/home/serg/Abk/mysql-4.1

into mysql.com:/home/jonas/src/mysql-4.1

into build.mysql.com:/users/rburnett/mysql-4.1

into rurik.mysql.com:/home/igor/dev/mysql-4.1-0

into mysql.com:/home/jonas/src/mysql-4.1

into ice.snake.net:/Volumes/ice2/MySQL/bk/mysql-4.1

Fix for MyISAM. Tests for MyISAM and HASH+BTREE.

into mysql.com:/home/jonas/src/mysql-4.1

into brandersnatch.localdomain:/home/dlenev/src/mysql-4.1-bg4302

into poseidon.(none):/home/tomas/mysql-4.1

into brandersnatch.localdomain:/home/dlenev/src/mysql-4.1-bg4302

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

into poseidon.(none):/home/tomas/mysql-4.1

into mysql.com:/home/mysql_src/mysql-4.0