mercurial/configitems.py

--- a/mercurial/configitems.py	Wed Jun 28 13:19:40 2017 +0200
+++ b/mercurial/configitems.py	Wed Jun 28 13:25:33 2017 +0200
@@ -59,6 +59,9 @@
 coreconfigitem('devel', 'all-warnings',
     default=False,
 )
+coreconfigitem('devel', 'bundle2.debug',
+    default=False,
+)
 coreconfigitem('patch', 'fuzz',
     default=2,
 )