Bug tax_rate

modules/purchase/purchase.py

@@ -519,6 +519,8 @@ class Purchase(
 
     @property
     def taxable_lines(self):
+        Date = Pool().get('ir.date')
+        tax_date = getattr(self, 'purchase_date', None) or Date.today()
         taxable_lines = []
         # In case we're called from an on_change we have to use some sensible
         # defaults
@@ -529,7 +531,7 @@ class Purchase(
                     getattr(line, 'taxes', None) or [],
                     getattr(line, 'unit_price', None) or Decimal(0),
                     getattr(line, 'quantity', None) or 0,
-                    None,
+                    tax_date,
                     ))
         return taxable_lines