Bug #31540 incorrect auto_increment values used for multi-row insert trigger

Description:
Duplicate key errors come up when a multi-row insert is done which fires a trigger.  If table "b" is a MyISAM table then everything works fine.
See how to repeat.

How to repeat:
create table a (a int, val char(1)) engine="InnoDB";
create table b (b int auto_increment primary key, val char(1)) engine="InnoDB";

create trigger a_after_insert after insert on a for each row insert into b set val = NEW.val;

insert into a values ( 123, 'a'), ( 123, 'b'), ( 123, 'c'), (123, 'd'), (123, 'e'), (123, 'f'), (123, 'g');

Unassigning from my lead, since this is an InnoDB only.

Fix is in our v5.1 trunk. It was fixed independently as part our code review prior  to the bug report.

Docs team:  This fix went into 5.1.23 and 6.0.4 (was included in snapshot 5.1-ss1989).

Noted in 5.1.23, 6.0.4 changelogs.

Spurious duplicate-key errors could occur for multiple-row inserts
into an InnoDB table that activate a trigger.