--- a/server/__init__.py	Wed Sep 16 11:23:51 2015 +0200
+++ b/server/__init__.py	Mon Sep 14 16:03:07 2015 +0200
@@ -29,6 +29,8 @@
 from glob import glob
 from contextlib import contextmanager
 
+from six import string_types
+
 from logilab.common.modutils import LazyObject
 from logilab.common.textutils import splitstrip
 from logilab.common.registry import yes
@@ -139,7 +141,7 @@
     if not debugmode:
         DEBUG = 0
         return
-    if isinstance(debugmode, basestring):
+    if isinstance(debugmode, string_types):
         for mode in splitstrip(debugmode, sep='|'):
             DEBUG |= globals()[mode]
     else: