Some optimizer hint warnings are returned as errors

CREATE TABLE t1 (id  int(11) NOT NULL auto_increment, f1 INT NOT NULL, PRIMARY KEY  (id));

INSERT INTO t1 (id, f1) VALUES (1,9),(2,0), (3,7);

CREATE TABLE t2 (id  int(11), f2 INT NOT NULL);

INSERT INTO t2 (id, f2) VALUES

(4,5),(3,3),(1,0),(1,3),(6,1),(2,0),(4,1),(2,7),(2,1),(1,0),(3,0),(5,8),(5,4),(3,9),(2,0),(7,2),(2,0),(1,8),(6,5),(4,1);

SET SQL_MODE='STRICT_TRANS_TABLES';

CREATE TABLE tn (fn_1 INT, fn_2 INT);

EXPLAIN EXTENDED

INSERT INTO tn (fn_1, fn_2) SELECT  /*+ JOIN_ORDER(t2,t1) JOIN_FIXED_ORDER() */ f1,f2 FROM t2  JOIN t1 ON t1.id=t2.id ORDER BY f1, f2;

EXPLAIN EXTENDED

INSERT INTO tn (fn_1, fn_2) SELECT  /*+ JOIN_ORDER(t1,t2) */ f1,f2 FROM t2 LEFT JOIN t1 ON t1.id=t2.id ORDER BY f1, f2;

drop table tn;

drop table t1, t2;

Warnings:

Warning	4210	Hint JOIN_FIXED_ORDER() is ignored as conflicting/duplicated

 At line 48: query 'EXPLAIN EXTENDED

INSERT INTO tn (fn_1, fn_2) SELECT  /*+ JOIN_ORDER(t1,t2) */ f1,f2 FROM t2 LEFT JOIN t1 ON t1.id=t2.id ORDER BY f1, f2' failed: ER_WARN_CONFLICTING_HINT (4210): Hint JOIN_ORDER(`t1`,`t2`) is ignored as conflicting/duplicated