Use stock_assign to compute product by location with future date

(transplanted from c934d6713653bd9a46ba1c1d566a172b9f055ccc)

product.py

@@ -208,7 +208,8 @@ class Product(OSV):
                 '))'
             today = date_obj.today(cursor, user, context=context)
             state_date_vals = [
-                'done', 'assigned', today, today,
+                'done', context.get('stock_assign') and 'assigned' or 'done',
+                today, today,
                 'done', 'assigned', 'draft',
                 context['stock_date_end'], today,
                 context['stock_date_end'], today,