LP:1002564 - Wrong result for a lookup query from a heap table

The following test case gives us a wrong result in MariaDB 5.2/5.5

CREATE TABLE t1 (
c1 VARCHAR(10) NOT NULL,
KEY i1 (c1(3))
) ENGINE=MEMORY DEFAULT CHARSET=latin1;
INSERT INTO t1 VALUES ('foo1'), ('bar2'), ('baz3');

SELECT * FROM t1 WHERE c1='bar2';

MariaDB [test]> SELECT * FROM t1 WHERE c1='bar2';
Empty set (0.00 sec)

(see also bug #47704 from bugs.mysql.com)