INSERT IGNORE on constraints result in ERROR rather than warning

The following INSERT IGNORE emits an error instead of a warning:

DROP TABLE IF EXISTS `my_table`;

CREATE TABLE `my_table` (
`first_col` char(63),
`second_col` char(63),
constraint `my_const` check (`first_col` != `second_col`)
);

INSERT IGNORE INTO `my_table` VALUES ('a', 'a');