MDEV-18635 The test case for bug mdev-16727 crashes the server

           in the tree bb-10.4-mdev7486

The crash was caused because after merge of bb-10.4-mdev7486 and
10.4 branches changes for mdev-16727 were missing.

mysql-test/main/in_subq_cond_pushdown.result

@@ -3836,13 +3836,24 @@ DROP TABLE t1;
 #             of multiple equalities
 #
 CREATE TABLE t1 (a varchar(1));
-INSERT INTO `t1` VALUES ('x'), ('y'), ('z');
+INSERT INTO t1 VALUES ('x'), ('y'), ('z');
 CREATE TABLE t2 (b varchar(1));
 INSERT INTO t2 VALUES ('x');
 CREATE TABLE t3 (c varchar(1));
 INSERT INTO t3 VALUES ('y');
 CREATE TABLE t4 (d varchar(1));
 INSERT INTO t4 VALUES ('x'), ('z');
+SELECT * FROM t1
+JOIN t2 ON (t1.a=t2.b)
+LEFT JOIN t3 ON (t1.a=t3.c)
+WHERE (t1.a) IN
+(
+SELECT t4.d
+FROM t4
+ORDER BY t4.d
+);
+a	b	c
+x	x	NULL
 DROP TABLE t1,t2,t3,t4;
 #
 # MDEV-17360: IN subquery predicate with outer reference in the left part

mysql-test/main/in_subq_cond_pushdown.test

@@ -799,7 +799,7 @@ DROP TABLE t1;
 --echo #
 
 CREATE TABLE t1 (a varchar(1));
-INSERT INTO `t1` VALUES ('x'), ('y'), ('z');
+INSERT INTO t1 VALUES ('x'), ('y'), ('z');
 
 CREATE TABLE t2 (b varchar(1));
 INSERT INTO t2 VALUES ('x');
@@ -810,15 +810,15 @@ INSERT INTO t3 VALUES ('y');
 CREATE TABLE t4 (d varchar(1));
 INSERT INTO t4 VALUES ('x'), ('z');
 
-# SELECT * FROM t1
-# JOIN t2 ON (t1.a=t2.b)
-# LEFT JOIN t3 ON (t1.a=t3.c)
-# WHERE (t1.a) IN
-# (
-#  SELECT t4.d
-#  FROM t4
-#  ORDER BY t4.d
-# );
+SELECT * FROM t1
+JOIN t2 ON (t1.a=t2.b)
+LEFT JOIN t3 ON (t1.a=t3.c)
+WHERE (t1.a) IN
+(
+  SELECT t4.d
+  FROM t4
+  ORDER BY t4.d
+);
 
 DROP TABLE t1,t2,t3,t4;
 

sql/opt_subselect.cc

@@ -5803,7 +5803,7 @@ Item *and_new_conditions_to_optimized_cond(THD *thd, Item *cond,
         if (equality->fix_fields(thd, NULL))
           return NULL;
       }
-      *cond_eq= &new_cond_equal;
+      (*cond_eq)->copy(new_cond_equal);
     }
     new_conds_list.append((List<Item> *)&new_cond_equal.current_level);