--- a/mercurial/ui.py	Wed Apr 19 23:10:05 2017 +0900
+++ b/mercurial/ui.py	Mon May 01 15:51:47 2017 +0200
@@ -59,6 +59,7 @@
 # uncomment these lines to enable some popular extensions
 # (see 'hg help extensions' for more info)
 #
+# churn =
 # pager =""",
 
     'cloned':
@@ -107,6 +108,7 @@
 # (see 'hg help extensions' for more info)
 #
 # blackbox =
+# churn =
 # pager =""",
 }