config root man

CREATE TABLE t (a INT PRIMARY KEY, b INT NOT NULL) ENGINE=InnoDB;
INSERT INTO t VALUES(1,2),(2,3);
SET DEBUG_SYNC='alter_table_inplace_after_lock_downgrade SIGNAL do WAIT_FOR m';
SET DEBUG_SYNC='innodb_after_inplace_alter_table SIGNAL scanned WAIT_FOR done';
CREATE INDEX tb ON t(b);
SET DEBUG_SYNC='now WAIT_FOR do';
SET DEBUG_SYNC='row_update_for_mysql_error SIGNAL m WAIT_FOR scanned';
UPDATE t SET a=2 WHERE a=1;
ERROR 23000: Duplicate entry '2' for key 'PRIMARY'
call mtr.add_suppression('InnoDB: record in index .*tb was not found on rollback, trying to insert');
SET DEBUG_SYNC='now SIGNAL done';
SET DEBUG_SYNC='RESET';
DROP TABLE t;