Fix debug assertions, it is possible that no request is associated to a data

transfer.

src/datawizard/copy-driver.c

@@ -192,7 +192,7 @@ static int copy_data_1_to_1_generic(data_state *state, uint32_t src_node, uint32
 int __attribute__((warn_unused_result)) driver_copy_data_1_to_1(data_state *state, uint32_t src_node, 
 		uint32_t dst_node, unsigned donotread, struct data_request_s *req, unsigned may_alloc)
 {
-	if (req->read)
+	if (!donotread)
 	{
 		STARPU_ASSERT(state->per_node[src_node].allocated);
 		STARPU_ASSERT(state->per_node[src_node].refcnt);