Index: location.py
===================================================================

--- ./modules/stock/location.py
+++ ./modules/stock/location.py
@@ -160,6 +160,11 @@
         return [(cls._rec_name,) + tuple(clause[1:])]
 
     @classmethod
+    def _quantity_grouping_and_key(cls):
+        product_id = Transaction().context['product']
+        return ('product', ), (product_id,)
+
+    @classmethod
     def get_quantity(cls, locations, name):
         pool = Pool()
         Product = pool.get('product.product')
@@ -189,11 +194,12 @@
 
         location_ids = [l.id for l in locations]
         product_id = Transaction().context['product']
+        grouping, key = cls._quantity_grouping_and_key()
         with Transaction().set_context(context):
             pbl = Product.products_by_location(location_ids=location_ids,
-                product_ids=[product_id], with_childs=True)
+                product_ids=[product_id], with_childs=True, grouping=grouping)
 
-        return dict((loc, pbl.get((loc, product_id), 0))
+        return dict((loc, pbl.get((loc,) + key, 0))
             for loc in location_ids)
 
     @classmethod