[FIX] stock: multiple orderpoints for a same location

commit 47654e98e0 modified a defaultdict by an OrderedDict.
When multiple orderpoints use the same location the key is the same and
location_data dict entry is removed for the new one.

This commit only call makedefault when there is not current entry for
the dict.

addons/stock/models/procurement.py

@@ -339,7 +339,8 @@ class ProcurementGroup(models.Model):
 
             for orderpoint in orderpoints:
                 key = self._procurement_from_orderpoint_get_grouping_key([orderpoint.id])
-                location_data[key] = makedefault()
+                if not location_data.get(key):
+                    location_data[key] = makedefault()
                 location_data[key]['products'] += orderpoint.product_id
                 location_data[key]['orderpoints'] += orderpoint
                 location_data[key]['groups'] = self._procurement_from_orderpoint_get_groups([orderpoint.id])