Fixed the bug mdev-12855.

This is actually a legacy bug:
SQL_SELECT::test_quick_select() was called
with SQL_SELECT::head not set.
It looks like that this problem can be
reproduced only on queries with ORDER BY
that use IN predicates converted to semi-joins.

mysql-test/r/subselect_sj2_mat.result

@@ -1579,3 +1579,25 @@ Warnings:
 Note	1003	select `test`.`t1`.`i` AS `i` from `test`.`t1` semi join (`test`.`t2`) where ((rand() < 0))
 drop table t1,t2;
 set optimizer_switch=@save_optimizer_switch;
+#
+# mdev-12855: materialization of a semi-join subquery + ORDER BY 
+#
+CREATE TABLE t1 (f1 varchar(8), KEY(f1)) ENGINE=InnoDB;
+INSERT INTO t1 VALUES ('qux'),('foo');
+CREATE TABLE t2 (f2 varchar(8)) ENGINE=InnoDB;
+INSERT INTO t2 VALUES ('bar'),('foo'),('qux');
+SELECT f1 FROM t1 
+WHERE f1 IN ( SELECT f2 FROM t2 WHERE f2 > 'bar' )
+HAVING f1 != 'foo'
+ORDER BY f1;
+f1
+qux
+explain SELECT f1 FROM t1 
+WHERE f1 IN ( SELECT f2 FROM t2 WHERE f2 > 'bar' )
+HAVING f1 != 'foo'
+ORDER BY f1;
+id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
+1	PRIMARY	t1	index	f1	f1	11	NULL	2	Using index
+1	PRIMARY	<subquery2>	eq_ref	distinct_key	distinct_key	11	func	1	
+2	MATERIALIZED	t2	ALL	NULL	NULL	NULL	NULL	3	Using where
+DROP TABLE t1,t2;

mysql-test/t/subselect_sj2_mat.test

@@ -283,3 +283,23 @@ select * from t1 where (rand() < 0) and i in (select i from t2);
 
 drop table t1,t2;
 set optimizer_switch=@save_optimizer_switch;
+
+--echo #
+--echo # mdev-12855: materialization of a semi-join subquery + ORDER BY 
+--echo #
+
+CREATE TABLE t1 (f1 varchar(8), KEY(f1)) ENGINE=InnoDB;
+INSERT INTO t1 VALUES ('qux'),('foo');
+CREATE TABLE t2 (f2 varchar(8)) ENGINE=InnoDB;
+INSERT INTO t2 VALUES ('bar'),('foo'),('qux');
+
+let $q=
+SELECT f1 FROM t1 
+WHERE f1 IN ( SELECT f2 FROM t2 WHERE f2 > 'bar' )
+HAVING f1 != 'foo'
+ORDER BY f1;
+
+eval $q;
+eval explain $q;
+
+DROP TABLE t1,t2;

sql/sql_select.cc

@@ -2759,8 +2759,11 @@ JOIN::exec()
       if (sort_table_cond)
       {
 	if (!curr_table->select)
+	{
 	  if (!(curr_table->select= new SQL_SELECT))
 	    DBUG_VOID_RETURN;
+	  curr_table->select->head= curr_table->table;
+        }
 	if (!curr_table->select->cond)
 	  curr_table->select->cond= sort_table_cond;
 	else
@@ -2846,7 +2849,7 @@ JOIN::exec()
 			    curr_join->select_limit,
 			    (select_options & OPTION_FOUND_ROWS ?
 			     HA_POS_ERROR : unit->select_limit_cnt),
-                            curr_join->group_list ? TRUE : FALSE))
+                            curr_join->group_list ? FALSE : TRUE))
 	DBUG_VOID_RETURN;
       sortorder= curr_join->sortorder;
       if (curr_join->const_tables != curr_join->table_count &&