Fix reporting of constraint violations for table partitioning.

After a tuple is routed to a partition, it has been converted from the
root table's row type to the partition's row type.  ExecConstraints
needs to report the failure using the original tuple and the parent's
tuple descriptor rather than the ones for the selected partition.

Amit Langote

src/backend/commands/tablecmds.c

@@ -1324,6 +1324,7 @@ ExecuteTruncate(TruncateStmt *stmt)
 						  rel,
 						  0,	/* dummy rangetable index */
 						  false,
+						  NULL,
 						  0);
 		resultRelInfo++;
 	}