Wrong result with DESC key on partitioned Spider table

--source include/have_partition.inc

INSTALL SONAME 'ha_spider';

SET spider_same_server_link= 1;

CREATE TABLE t1 (a INT PRIMARY KEY);

CREATE TABLE t2 (a INT PRIMARY KEY);

eval 

CREATE TABLE t (a INT, PRIMARY KEY (a DESC)) ENGINE=SPIDER

COMMENT "host '127.0.0.1', port '$MASTER_MYPORT', user 'root'"

PARTITION BY RANGE (a) 

(PARTITION p1 VALUES LESS THAN (4) COMMENT "table 't1'",

 PARTITION p2 VALUES LESS THAN (MAXVALUE) COMMENT "table 't2'");

INSERT INTO t VALUES (1),(2),(10),(11);

SELECT * FROM t WHERE a > 1 ORDER BY a;

SELECT * FROM t WHERE a > 1 ORDER BY a;

a

SELECT * FROM t WHERE a > 1 ORDER BY a;

a

2

10

11