Wrong result upon forcing fulltext index on InnoDB table

--source include/have_innodb.inc

CREATE TABLE t (a varchar(128), fulltext(a)) engine=InnoDB;

INSERT INTO t VALUES ('Alabama'),('Washington');

SELECT a FROM t FORCE INDEX(a) ORDER BY a;

ALTER TABLE t ADD PRIMARY KEY(a);

SELECT a FROM t FORCE INDEX(a) ORDER BY a;

# Cleanup

DROP TABLE t;

CREATE TABLE t (a varchar(128), fulltext(a)) engine=InnoDB;

INSERT INTO t VALUES ('Alabama'),('Washington');

SELECT a FROM t FORCE INDEX(a) ORDER BY a;

a

Alabama

Washington

ALTER TABLE t ADD PRIMARY KEY(a);

SELECT a FROM t FORCE INDEX(a) ORDER BY a;

a

DROP TABLE t;

INSERT INTO t VALUES ('Alabama'),('Washington');

EXPLAIN EXTENDED SELECT a FROM t FORCE INDEX(a) ORDER BY a;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	SIMPLE	t	ALL	NULL	NULL	NULL	NULL	2	100.00	Using filesort

Warnings:

Note	1003	select `test`.`t`.`a` AS `a` from `test`.`t` FORCE INDEX (`a`) order by `test`.`t`.`a`

ALTER TABLE t ADD PRIMARY KEY(a);

EXPLAIN EXTENDED SELECT a FROM t FORCE INDEX(a) ORDER BY a;

id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra

1	SIMPLE	t	index	NULL	a	130	NULL	2	100.00	

Warnings:

Note	1003	select `test`.`t`.`a` AS `a` from `test`.`t` FORCE INDEX (`a`) order by `test`.`t`.`a`