Incorrect result in JOIN with IN subquery

When a CHAR column containing a non-numeric string (e.g., 'Kx') is compared against a BIT column via an IN subquery, the server returns rows unexpectedly.

How to repeat:

• CREATE TABLE t1(c1 BIT);

  CREATE TABLE t2(c1 CHAR(20));

  INSERT INTO t2 (c1) VALUES ('Kx');

  INSERT INTO t1 (c1) VALUES (b'0');

  INSERT INTO t1 (c1) VALUES (b'1');

  SELECT t1.c1 FROM t1 JOIN t2 ON (t2.c1 IN (SELECT t1.c1 FROM t1));

  /* Expected: Empty set

  Actual:

  +------------+

  | c1 |

  +------------+

  | 0x00 |

  | 0x01 |

  +------------+

  */