MDEV-515: Improve test coverage

Cover dict_index_t::clear() for TEMPORARY TABLE

mysql-test/suite/innodb/r/insert_into_empty.result

@@ -45,6 +45,10 @@ SET tx_read_only=1;
 BEGIN;
 INSERT INTO t2 VALUES(0);
 INSERT INTO t VALUES(0);
+ROLLBACK;
+BEGIN;
+INSERT INTO t2 VALUES(0);
+INSERT INTO t VALUES(0);
 COMMIT;
 INSERT INTO t VALUES(0);
 DROP TEMPORARY TABLE t,t2;

mysql-test/suite/innodb/t/insert_into_empty.test

@@ -51,6 +51,10 @@ SET tx_read_only=1;
 BEGIN;
 INSERT INTO t2 VALUES(0);
 INSERT INTO t VALUES(0);
+ROLLBACK;
+BEGIN;
+INSERT INTO t2 VALUES(0);
+INSERT INTO t VALUES(0);
 COMMIT;
 INSERT INTO t VALUES(0);