BUG#21033 The error log of mysqld shows useless information, and hides the real error.

storage/ndb/src/ndbapi/Ndb.cpp:
  Ndb.closeTransaction() modifies the value of Ndb.theError.code, 
  but the error code shouldn't be changed here. 
  Mysqld will use the returning error code to log the correct information.

storage/ndb/src/ndbapi/Ndb.cpp

@@ -1147,9 +1147,14 @@ Ndb::opTupleIdOnNdb(const NdbTableImpl* table,
     theError.code = tOperation->theError.code;
   DBUG_ASSERT(theError.code != 0);
 
+  NdbError savedError;
+  savedError = theError;
+
   if (tConnection != NULL)
     this->closeTransaction(tConnection);
 
+  theError = savedError;
+
   DBUG_RETURN(-1);
 }