Correct a bug (that I introduced, after using Oracle's database software for 
too many years) where the length of the database-sent data is incorrectly 
used to infer NULLness.

into  mysql.com:/home/psergey/mysql-5.0-best_access_path_j-push

into  mysql.com:/home/psergey/mysql-5.0-best_access_path_j-push

into  xiphis.org:/home/antony/work2/mysql-5.0-engines-merge

into  xiphis.org:/home/antony/work2/p1-bug10952.1

  "alter table from MyISAM to MERGE lost data without errors and warnings"
  Add new handlerton flag which prevent user from altering table storage
  engine to storage engines which would lose data. Both 'blackhole' and 
  'merge' are marked with the new flag.
  Tests included.

into  mysql.com:/home/marty/MySQL/mysql-5.0

into  mysql.com:/home/marty/MySQL/mysql-5.0

into  neptunus.(none):/home/msvensson/mysql/mysql-5.0

into  neptunus.(none):/home/msvensson/mysql/mysql-5.0-maint

No commit message

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

Add function 'vio_end' that will cleanup resources allocated by vio and the components it uses.

into  neptunus.(none):/home/msvensson/mysql/mysql-5.0-maint

into  neptunus.(none):/home/msvensson/mysql/mysql-5.0-maint

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

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

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

into  mysql.com:/usr_rh9/home/elkin.rh9/MySQL/Merge/5.0-bug19136

recalculating results

find_best() call best_access_path().

into  mysql.com:/usr_rh9/home/elkin.rh9/MySQL/Merge/5.0-bug19136

into  mysql.com:/usr_rh9/home/elkin.rh9/MySQL/FIXES/4.1-bug19136_unass_user_var

A query with a group by and having clauses could return a wrong
result set if the having condition contained a constant conjunct 
evaluated to FALSE.
It happened because the pushdown condition for table with
grouping columns lost its constant conjuncts.
Pushdown conditions are always built by the function make_cond_for_table
that ignores constant conjuncts. This is apparently not correct when
constant false conjuncts are present.

into mysql.com:/home/psergey/mysql-5.0-bug16798-merge

into mysql.com:/home/psergey/mysql-4.1-bug16798

into  mysql.com:/home/tomash/src/mysql_ab/mysql-5.0-merge

into  mysql.com:/home/tomash/src/mysql_ab/mysql-4.1-bug16501

into  mysql.com:/home/tomash/src/mysql_ab/mysql-4.1-bug16501

into  mysql.com:/home/mydev/mysql-4.1-bug10405

into  mysql.com:/home/mydev/mysql-5.0-bug10405

into mysql.com:/home/psergey/mysql-4.1-bug16798

into mysql.com:/home/psergey/mysql-5.0-bug16798-merge

The bug was as follows: When merge_key_fields() encounters "t.key=X OR t.key=Y" it will 
try to join them into ref_or_null access via "t.key=X OR NULL". In order to make this 
inference it checks if Y<=>NULL, ignoring the fact that value of Y may be not yet known.

The fix is that the check if Y<=>NULL is made only if value of Y is known (i.e. it is a
constant).
TODO: When merging to 5.0, replace used_tables() with const_item() everywhere in merge_key_fields().

after merge.

Concurrent read and update of privilege structures (like simultaneous
run of SHOW GRANTS and ADD USER) could result in server crash.

Ensure that proper locking of ACL structures is done.

No test case is provided because this bug can't be reproduced
deterministically.

into  mysql.com:/home/tomash/src/mysql_ab/mysql-5.0-merge