diff -r abb92b3d370e -r c42feb5f3143 mercurial/ui.py
--- a/mercurial/ui.py	Tue Jan 17 17:25:48 2017 +0100
+++ b/mercurial/ui.py	Mon Feb 20 12:12:08 2017 +0100
@@ -127,6 +127,8 @@
     raise error.SignalInterrupt
 
 class ui(object):
+    # color mode: see mercurial/color.py for possible value
+    _colormode = None
     def __init__(self, src=None):
         """Create a fresh new ui object if no src given