MDEV-8709 Row equality elements do not get propagated

The problem was fixed earlier by one of the MDEV-8728 subtasks.
Adding a test case only.

Author: Alexander Barkov

mysql-test/r/row.result

@@ -489,3 +489,25 @@ SELECT i FROM t1 WHERE ROW(1,2) = (SELECT 1,3 FROM DUAL WHERE 1 = 0);
 i
 DROP TABLE t1;
 End of 5.1 tests
+#
+# Start of 10.1 tests
+#
+#
+# MDEV-8709 Row equality elements do not get propagated
+#
+CREATE TABLE t1 (a INT, b INT);
+INSERT INTO t1 VALUES (10,10),(20,20);
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=10 AND b=10 AND a>=10;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where ((`test`.`t1`.`a` = 10) and (`test`.`t1`.`b` = 10))
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE (a,b)=(10,10) AND a>=10;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	filtered	Extra
+1	SIMPLE	t1	ALL	NULL	NULL	NULL	NULL	2	100.00	Using where
+Warnings:
+Note	1003	select `test`.`t1`.`a` AS `a`,`test`.`t1`.`b` AS `b` from `test`.`t1` where ((`test`.`t1`.`a` = 10) and (`test`.`t1`.`b` = 10))
+DROP TABLE t1;
+#
+# End of 10.1 tests
+#

mysql-test/t/row.test

@@ -285,3 +285,21 @@ SELECT i FROM t1 WHERE ROW(1,2) = (SELECT 1,3 FROM DUAL WHERE 1 = 0);
 DROP TABLE t1;
 
 --echo End of 5.1 tests
+
+--echo #
+--echo # Start of 10.1 tests
+--echo #
+
+--echo #
+--echo # MDEV-8709 Row equality elements do not get propagated
+--echo #
+CREATE TABLE t1 (a INT, b INT);
+INSERT INTO t1 VALUES (10,10),(20,20);
+# Checking that the a>=10 part gets optimized away in both scalar and row notations
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE a=10 AND b=10 AND a>=10;
+EXPLAIN EXTENDED SELECT * FROM t1 WHERE (a,b)=(10,10) AND a>=10;
+DROP TABLE t1;
+
+--echo #
+--echo # End of 10.1 tests
+--echo #