FOUND_ROWS() return incorrect value when using DISTINCT

--

-- bugMariaDB.sql

--

-- Use:

-- $ mysql -uroot -p < bugMariaDB.sql

--

DROP DATABASE IF EXISTS bugtest;

CREATE DATABASE bugtest;

USE bugtest;

CREATE TABLE tbltestA (

  numA   INTEGER PRIMARY KEY

, dated  DATETIME

, parity INTEGER

);

CREATE TABLE tbltestB (

  id_numA INTEGER

, id_part INTEGER

, status  CHAR(16) DEFAULT ''

, PRIMARY KEY (id_numA, id_part)

);

delimiter //

  CREATE PROCEDURE seqInsert (len INT)

  BEGIN

    DECLARE i INT DEFAULT 1;

    WHILE i <= len DO

      INSERT INTO tbltestA (numA, dated, parity) VALUES (i, UTC_TIMESTAMP(), i%2);

      INSERT INTO tbltestB (id_numA, id_part, status) VALUES (i, 0, 'ok');

      INSERT INTO tbltestB (id_numA, id_part, status) VALUES (i, 1, 'ok');

      INSERT INTO tbltestB (id_numA, id_part, status) VALUES (i, 2, 'ko');

      INSERT INTO tbltestB (id_numA, id_part, status) VALUES (i, 3, 'ko');

      INSERT INTO tbltestB (id_numA, id_part, status) VALUES (i, 4, 'ok');

      INSERT INTO tbltestB (id_numA, id_part, status) VALUES (i, 5, 'ok');

      SET i = i + 1;

    END WHILE;

  END //

delimiter ;

CALL seqInsert(512);

-- Tests to reproduce the bug ------------------------------------------------

-- NOTE: DISTINCT is necessary to reproduce the bug

-- TEST 1 --------------------------------------------------------------------

SELECT SQL_CALC_FOUND_ROWS DISTINCT numA,dated,status FROM tbltestA JOIN tbltestB ON id_numA=numA WHERE numA <= 256 AND parity=0 AND status='ok' ORDER BY dated DESC, numA DESC LIMIT 45;

SELECT FOUND_ROWS();

-- OK: 128

SELECT SQL_CALC_FOUND_ROWS DISTINCT numA,dated,status FROM tbltestA JOIN tbltestB ON id_numA=numA WHERE numA <= 256 AND parity=0 AND status='ok' ORDER BY dated DESC, numA DESC LIMIT 46;

SELECT FOUND_ROWS();

-- ERR: 46 (46 in MariaDB, 128 in MySQL)

-- TEST 2 --------------------------------------------------------------------

SELECT SQL_CALC_FOUND_ROWS DISTINCT numA,dated,status FROM tbltestA JOIN tbltestB ON id_numA=numA WHERE numA <= 256 AND parity=0 AND status='ok' ORDER BY dated DESC, numA DESC LIMIT 50 OFFSET 0;

SELECT FOUND_ROWS();

-- ERR: 50 (50 in MariaDB, 128 in MySQL)

SELECT SQL_CALC_FOUND_ROWS DISTINCT numA,dated,status FROM tbltestA JOIN tbltestB ON id_numA=numA WHERE numA <= 256 AND parity=0 AND status='ok' ORDER BY dated DESC, numA DESC LIMIT 50 OFFSET 50;

SELECT FOUND_ROWS();

-- ERR: 100 (100 in MariaDB, 128 in MySQL)