diff -r 79ff784cd8af -r 7f6b5f023884 transaction.py
--- a/transaction.py	Fri Sep 11 18:01:36 2015 +0200
+++ b/transaction.py	Fri Sep 11 18:05:38 2015 +0200
@@ -17,7 +17,7 @@
 # with CubicWeb.  If not, see <http://www.gnu.org/licenses/>.
 """ undoable transaction objects. """
 __docformat__ = "restructuredtext en"
-_ = unicode
+from cubicweb import _
 
 from cubicweb import RepositoryError