fixing wrong value for "examined rows" when UNION's are used.

mysql-test/r/union.result:
  result for a test case for the wrong examined rows with UNION's
mysql-test/t/union.test:
  test case for the wrong examined rows with UNION's
sql/sql_union.cc:
  a patch for the wrong examined rows with UNION's

mysql-test/r/union.result

@@ -872,6 +872,22 @@ count(*)
 show status like 'Slow_queries';
 Variable_name	Value
 Slow_queries	3
+flush status;
+select a from t1 where b not in (1,2,3) union select a from t1 where b not in (4,5,6);
+a
+4
+5
+3
+6
+7
+8
+9
+10
+1
+2
+show status like 'Slow_queries';
+Variable_name	Value
+Slow_queries	1
 drop table t1;
 create table t1 (   RID int(11) not null default '0',   IID int(11) not null default '0',    nada varchar(50)  not null,NAME varchar(50) not null,PHONE varchar(50) not null) engine=MyISAM;
 insert into t1 ( RID,IID,nada,NAME,PHONE) values (1, 1, 'main', 'a', '111'), (2, 1, 'main', 'b', '222'), (3, 1, 'main', 'c', '333'), (4, 1, 'main', 'd', '444'), (5, 1, 'main', 'e', '555'), (6, 2, 'main', 'c', '333'), (7, 2, 'main', 'd', '454'), (8, 2, 'main', 'e', '555'), (9, 2, 'main', 'f', '666'), (10, 2, 'main', 'g', '777');

mysql-test/t/union.test

@@ -481,6 +481,10 @@ select count(*) from t1 where b=13 union select count(*) from t1 where a=7;
 show status like 'Slow_queries';
 select count(*) from t1 where a=7 union select count(*) from t1 where b=13;
 show status like 'Slow_queries';
+# additional test for examined rows
+flush status;
+select a from t1 where b not in (1,2,3) union select a from t1 where b not in (4,5,6); 
+show status like 'Slow_queries';
 drop table t1;
 
 #

sql/sql_union.cc

@@ -466,11 +466,14 @@ int st_select_lex_unit::exec()
 	}
 	res= sl->join->error;
 	offset_limit_cnt= sl->offset_limit;
-	if (!res && union_result->flush())
+	if (!res)
 	{
-          examined_rows+= thd->examined_row_count;
-	  thd->lex->current_select= lex_select_save;
-	  DBUG_RETURN(1);
+	  examined_rows+= thd->examined_row_count;
+	  if (union_result->flush())
+	  {
+	    thd->lex->current_select= lex_select_save;
+	    DBUG_RETURN(1);
+	  }
 	}
       }
       if (res)