--- a/cubicweb/rtags.py	Thu Nov 24 16:58:27 2016 +0100
+++ b/cubicweb/rtags.py	Thu Nov 24 16:58:50 2016 +0100
@@ -38,16 +38,17 @@
 
 
 import logging
-from warnings import warn
 
 from six import string_types
 
 from logilab.common.logging_ext import set_log_methods
 from logilab.common.registry import RegistrableInstance, yes
 
+
 def _ensure_str_key(key):
     return tuple(str(k) for k in key)
 
+
 class RegistrableRtags(RegistrableInstance):
     __registry__ = 'uicfg'
     __select__ = yes()