Bug#40515: Query on a partitioned table does not return

'lock wait timeout exceeded'

Problem was a bug in the implementation of scan in partitioning
which masked the error code from the partition's handler.

Fixed by returning the value from the underlying handler.

mysql-test/suite/parts/r/partition_special_innodb.result:
  Bug#40515: Query on a partitioned table does not return
  'lock wait timeout exceeded'
  
  Updated test result
mysql-test/suite/parts/t/partition_special_innodb.test:
  Bug#40515: Query on a partitioned table does not return
  'lock wait timeout exceeded'
  
  Updated test case for covering the bug.
sql/ha_partition.cc:
  Bug#40515: Query on a partitioned table does not return
  'lock wait timeout exceeded'
  
  Removing redeclaration of result variable,
  which resulted in never returning the correct return value.

mysql-test/suite/parts/r/partition_special_innodb.result

@@ -213,5 +213,10 @@ START TRANSACTION;
 INSERT INTO t1 VALUES (NULL, 'first row t2');
 SET autocommit=OFF;
 ALTER TABLE t1 AUTO_INCREMENT = 10;
+ERROR HY000: Lock wait timeout exceeded; try restarting transaction
 INSERT INTO t1 VALUES (NULL, 'second row t2');
+SELECT a,b FROM t1 ORDER BY a;
+a	b
+1	first row t2
+2	second row t2
 DROP TABLE t1;

mysql-test/suite/parts/t/partition_special_innodb.test

@@ -68,10 +68,12 @@ INSERT INTO t1 VALUES (NULL, 'first row t2');
 
 --connection con2
 SET autocommit=OFF;
+--error ER_LOCK_WAIT_TIMEOUT
 ALTER TABLE t1 AUTO_INCREMENT = 10;
 
 --connection con1
 INSERT INTO t1 VALUES (NULL, 'second row t2');
+SELECT a,b FROM t1 ORDER BY a;
 --disconnect con2
 --disconnect con1
 --connection default

sql/ha_partition.cc

@@ -3431,7 +3431,7 @@ int ha_partition::rnd_next(uchar *buf)
   
   while (TRUE)
   {
-    int result= file->rnd_next(buf);
+    result= file->rnd_next(buf);
     if (!result)
     {
       m_last_part= part_id;