Fix missing data unlink on memchunk reuse

src/datawizard/memalloc.c

@@ -524,6 +524,7 @@ static void reuse_mem_chunk(unsigned node, struct _starpu_data_replicate *new_re
 	if (old_replicate)
 	{
 		_starpu_data_unregister_ram_pointer(old_replicate->handle, node);
+		old_replicate->mc = NULL;
 		old_replicate->allocated = 0;
 		old_replicate->automatically_allocated = 0;
 		old_replicate->initialized = 0;