Item_func::agg_arg_collations()
  Item_func::arr_arg_collations_for_comparison()
 to aggregate argument collations.
It helps to reuse a lot of code.

into narttu.mysql.fi:/my/mysql-4.1

into bar.mysql.r18.ru:/usr/home/bar/mysql-4.1

into sanja.is.com.ua:/home/bell/mysql/bk/work-4.1

  ROW('a','b','c) = ROW('A' collate latin1_bin,'b','c') returns 0
When a number is compared to a string, character sets and 
collations are not aggregated. e.g. this returned error in 4.1.0:

SELECT 1=_latin2'1';
because character sets was aggregated, and 1 was considered as
a string of latin1 charset during this aggregation.

into narttu.mysql.fi:/my/mysql-4.1

into sanja.is.com.ua:/home/bell/mysql/bk/work-4.1

into sanja.is.com.ua:/home/bell/mysql/bk/work-err-4.1

into mashka.mysql.fi:/home/my/mysql-4.1

into sanja.is.com.ua:/home/bell/mysql/bk/work-err-4.1

into myvenu.com:/home/venu/work/sql/dev-4.1

  Minor fixups for SQLSTATE values to be compatible with ODBC spec

Earlier it could have failed in some special cases.

Fixed bug in ALTER TABLE ... MODIFY integer-column
Added ref_or_null optimization (needed for subqueries)

into sanja.is.com.ua:/home/bell/mysql/bk/work-union-4.1

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

(resolving fields of reduced subselect)

into sanja.is.com.ua:/home/bell/mysql/bk/work-cset-4.1

test moved to other bug