Migration to python-sql

review1001002

product.py

@@ -2,7 +2,7 @@
 #this repository contains the full copyright notices and license terms.
 from trytond.model import ModelSQL, fields
 from trytond.pyson import Eval, Or
-from trytond.backend import TableHandler
+from trytond import backend
 from trytond.transaction import Transaction
 from trytond.pool import PoolMeta
 
@@ -125,6 +125,7 @@ class CategoryCustomerTax(ModelSQL):
 
     @classmethod
     def __register__(cls, module_name):
+        TableHandler = backend.get('TableHandler')
         cursor = Transaction().cursor
         # Migration from 1.6 product renamed into category
         table = TableHandler(cursor, cls)
@@ -146,6 +147,7 @@ class CategorySupplierTax(ModelSQL):
 
     @classmethod
     def __register__(cls, module_name):
+        TableHandler = backend.get('TableHandler')
         cursor = Transaction().cursor
         # Migration from 1.6 product renamed into category
         table = TableHandler(cursor, cls)