In the GROUP BY clause, MariaDB incorrectly handled ' ' and NULL

CREATE TABLE t0 (

c0 TEXT NOT NULL

);

INSERT INTO t0 VALUES (' '), ('dadfad'), ('2342dfad'), ('2dfad');

CREATE TABLE t1 (

c0 TEXT NOT NULL

);

INSERT INTO t1 VALUES ('xxx'), ('3gf'), (''), ('dddd');

SELECT count(t1.c0) FROM t1 LEFT OUTER JOIN t0 ON t0.c0 = t1.c0 GROUP BY t0.c0;

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

| count(t1.c0) |

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

|            4 |

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

MariaDB> SELECT count(t1.c0) FROM t1 LEFT OUTER JOIN t0 ON t0.c0 = t1.c0 GROUP BY t0.c0;

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

| count(t1.c0) |

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

|            3 |

|            1 |

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

2 rows in set (0.004 sec)