ndb - bug#23200

  this changes lock taken during peek, to decrease likelyhood of transaction abort
  


sql/ha_ndbcluster.cc:
  use exclusive lock in peek, as peek is used just before insert/update

sql/ha_ndbcluster.cc

@@ -1588,7 +1588,9 @@ int ha_ndbcluster::peek_indexed_rows(const byte *record)
   int res;
   DBUG_ENTER("peek_indexed_rows");
 
-  NdbOperation::LockMode lm= NdbOperation::LM_Read;
+  NdbOperation::LockMode lm=
+    (NdbOperation::LockMode)get_ndb_lock_type(m_lock.type);
+  
   first= NULL;
   if (table->s->primary_key != MAX_KEY)
   {