diff --git a/.gitignore b/.hgignore
similarity index 87%
rename from .gitignore
rename to .hgignore
index 88532e8..e2b39b0 100644
--- a/.gitignore
+++ b/.hgignore
@@ -1,4 +1,4 @@
-*.pyc
+syntax: glob
 build/*
 mds_cashbook_bookcategory.egg-info/*
 dist/*
diff --git a/ir.py b/ir.py
index 182092e..0e71a97 100644
--- a/ir.py
+++ b/ir.py
@@ -3,6 +3,7 @@
 # The COPYRIGHT file at the top level of this repository contains the
 # full copyright notices and license terms.
 
+from trytond.transaction import Transaction
 from trytond.pool import PoolMeta
 
 
@@ -13,9 +14,7 @@ class Rule(metaclass=PoolMeta):
     def _context_modelnames(cls):
         """ list of models to add 'user_id' to context
         """
-        result = super(Rule, cls)._context_modelnames()
-        return result | {
-            'cashbook.bookcategory',
-        }
+        return super(Rule, cls)._context_modelnames() + [
+            'cashbook.bookcategory']
 
 # end Rule