Incorrect Result for IN Subquery on indexed CHAR Column

An IN (subquery) expression returns an incorrect result if the column in the subquery is a CHAR or VARCHAR type with a UNIQUE index.The issue is also reproducible if the table is created with `CREATE TABLE t114 (c1 VARCHAR(10), UNIQUE (c1(1)));`. Removing the UNIQUE index produces the correct result.

drop TABLE IF EXISTS t114;

CREATE TABLE t114 (c1 CHAR, UNIQUE (c1));

INSERT t114 () VALUES ('u');

select ('uH' IN (SELECT t114.c1 FROM t114)) from t114;

-- 1

drop TABLE IF EXISTS t114;

CREATE TABLE t114 (c1 CHAR);

INSERT t114 () VALUES ('u');

select ('uH' IN (SELECT t114.c1 FROM t114)) from t114;

-- 0