Fix of non-deterministic results.

mysql-test/r/user_var.result

@@ -348,10 +348,10 @@ select @a:=f3, count(f3) from t1 group by 1 desc;
 1.5	4
 select @a:=f4, count(f4) from t1 group by 1 desc;
 @a:=f4	count(f4)
-1.6	4
 1.6	1
-1.6	2
 1.6	1
+1.6	2
+1.6	4
 drop table t1;
 create table t1 (f1 int);
 insert into t1 values (2), (1);

mysql-test/t/user_var.test

@@ -235,6 +235,7 @@ select @a:=f1, count(f1) from t1 group by 1 desc;
 select @a:=f1, count(f1) from t1 group by 1 asc;
 select @a:=f2, count(f2) from t1 group by 1 desc;
 select @a:=f3, count(f3) from t1 group by 1 desc;
+--sorted_result
 select @a:=f4, count(f4) from t1 group by 1 desc;
 drop table t1;