different fix for internal Oracle MySQL bug#16324629 that doesn't crash

(simply, copied from FederatedX)

mysql-test/suite/federated/federated_maybe_16324629.result

+CREATE DATABASE federated;
+CREATE DATABASE federated;
+create table federated.t1 (a int, b int, unique key (a), key (b));
+create table t1 (a int, b int, unique key (a), key (b))
+engine=federated CONNECTION='mysql://root@127.0.0.1:SLAVE_PORT/federated/t1';
+insert into t1 values (3, 3), (7, 7);
+delete t1 from t1 where a = 3;
+select * from t1;
+a	b
+3	3
+7	7
+drop table t1;
+DROP TABLE IF EXISTS federated.t1;
+DROP DATABASE IF EXISTS federated;
+DROP TABLE IF EXISTS federated.t1;
+DROP DATABASE IF EXISTS federated;

mysql-test/suite/federated/federated_maybe_16324629.test

+#
+# Inspired by a bug fix for internal Oracle MySQL bug#16324629
+#
+source include/federated.inc;
+
+connection slave;
+create table federated.t1 (a int, b int, unique key (a), key (b));
+
+connection master;
+
+--replace_result $SLAVE_MYPORT SLAVE_PORT
+eval create table t1 (a int, b int, unique key (a), key (b))
+ engine=federated CONNECTION='mysql://root@127.0.0.1:$SLAVE_MYPORT/federated/t1';
+
+insert into t1 values (3, 3), (7, 7);
+delete t1 from t1 where a = 3;
+select * from t1;
+drop table t1;
+
+connection slave;
+connection default;
+source include/federated_cleanup.inc;
+

storage/federated/ha_federated.cc

@@ -2744,7 +2744,8 @@ void ha_federated::position(const uchar *record __attribute__ ((unused)))
 {
   DBUG_ENTER("ha_federated::position");
   
-  DBUG_ASSERT(stored_result);
+  if (!stored_result)
+    DBUG_VOID_RETURN;
 
   position_called= TRUE;
   /* Store result set address. */