crashes mysqld": implementation for a generic item tree modifications
registry. Every item tree modification which should be rolled back for
subsequent execution of a prepared statement or stored procedure should
be saved in the registry. All such modifications are rolled back at once
during cleanup stage of PS.
Actual fix for the bug just adds a call to register modifications to
convert_constant_item.
Post review fixes implemented.

and testcases

into mysql.com:/home/dlenev/src/mysql-4.1-bf

introduced during implementation of TIMESTAMP columns, which are able 
to store NULLs (Unfortunately it is impossible to write test case for
this. Kudos to Holyfoot for noticing it!)

into deer.(none):/home/hf/work/mysql-4.1.5730

  Fix typos in previous push

into hundin.mysql.fi:/home/heikki/mysql-4.1

into poseidon.ndb.mysql.com:/home/tomas/mysql-4.1

  Raise maximum column prefix len to 767 bytes, so that MySQL can create a column prefix index of 255 UTF-8 characters (each takes 3 bytes at the maximum); add comments about why innobase_get_at_most_n_mbchars() works ok
dict0mem.h:
  Raise maximum column prefix len to 767 bytes, so that MySQL can create a column prefix index of 255 UTF-8 characters (each takes 3 bytes at the maximum)
row0mysql.c:
  If MySQL tries to create a column prefix index longer that 255 UTF-8 characters, give an error, and drop the table from the InnoDB internal data dictionary. MySQL did not drop the table there in its own error handling.

into hundin.mysql.fi:/home/marko/j/mysql-4.1

into hundin.mysql.fi:/home/marko/j/mysql-4.1

removed staus flag

  Fix compiler warning

into mysql.com:/home/dlenev/src/mysql-4.1-ryan

into mysql.com:/M41/mysql-4.1

into mysql.com:/home/dlenev/src/mysql-4.1-ryan

into mysql.com:/home/dlenev/src/mysql-4.1-ryan

treated as DEFAULT NULL columns (independently from their position in
table).

(still to be discussed with Monty, Brian, Trudy et al. before push)

into poseidon.ndb.mysql.com:/home/tomas/mysql-4.1-ndb-merge

into poseidon.ndb.mysql.com:/home/tomas/mysql-4.1

bug #5872, transactions should only be restarted with transaction.on flag off if execute_commit has been performed
added testcase for this
use force send for all executes

with the system-reserved (and system-defined) '_REENTRANT' 
CPP identifier.
Especially, it must not be "undefine"d, because the Tru64 compiler
needs it if threads are enabled.

into poseidon.ndb.mysql.com:/home/tomas/mysql-4.1-ndb-merge

switch to using my_ for heap allocations

  ctype_recode does not hang anymore. Small fix after Marko's change.