py: Replace mp_const_stop_iteration object with MP_OBJ_NULL.
diff --git a/py/objarray.c b/py/objarray.c
index 69f60e0..d77a101 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -64,7 +64,7 @@
     mp_obj_t iterable = rt_getiter(initializer);
     mp_obj_t item;
     int i = 0;
-    while ((item = rt_iternext(iterable)) != mp_const_stop_iteration) {
+    while ((item = rt_iternext(iterable)) != MP_OBJ_NULL) {
         if (len == 0) {
             array_append(array, item);
         } else {
@@ -212,7 +212,7 @@
     if (self->cur < self->array->len) {
         return mp_binary_get_val(self->array->typecode, self->array->items, self->cur++);
     } else {
-        return mp_const_stop_iteration;
+        return MP_OBJ_NULL;
     }
 }