Manually ported this bug fix from 4.0: 
 Fix InnoDB bug #6287: if one uses INSERT IGNORE to insert several rows at a time, and the first inserts are ignored because of a duplicate key collision, then InnoDB in a replication slave assigns AUTO_INCREMENT values 1 bigger than in the master


sql/ha_innodb.cc:
  Fix InnoDB bug #6287: if one uses INSERT IGNORE to insert several rows at a time, and the first inserts are ignored because of a duplicate key collision, then InnoDB in a replication slave assigns AUTO_INCREMENT values 1 bigger than in the master