Wrong result upon aggregate function with SQL_BUFFER_RESULT

CREATE TABLE t1 (pk INT PRIMARY KEY);

INSERT INTO t1 VALUES (1),(2);

CREATE TABLE t2 (a INT);

INSERT INTO t2 VALUES (1),(2);

SELECT SQL_BUFFER_RESULT MIN(pk) FROM t1, t2;

SELECT MIN(pk) FROM t1, t2;

DROP TABLE t1, t2;

SELECT SQL_BUFFER_RESULT MIN(pk) FROM t1, t2;

MIN(pk)

NULL

SELECT MIN(pk) FROM t1, t2;

MIN(pk)

1

commit 38058c04a4fc021f381f8000e40ed23bd4fb8d75

Commit:     Monty

CommitDate: Tue Feb 8 14:32:29 2022 +0200

    MDEV-26585 Wrong query results when `using index for group-by`