diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -483,7 +483,7 @@ class cg1packer(object):
             bundlecaps = set()
         self._bundlecaps = bundlecaps
         # experimental config: bundle.reorder
-        reorder = repo.ui.config('bundle', 'reorder', 'auto')
+        reorder = repo.ui.config('bundle', 'reorder')
         if reorder == 'auto':
             reorder = None
         else:
diff --git a/mercurial/configitems.py b/mercurial/configitems.py
--- a/mercurial/configitems.py
+++ b/mercurial/configitems.py
@@ -67,6 +67,10 @@ coreconfigitem('bookmarks', 'pushing',
 coreconfigitem('bundle', 'mainreporoot',
     default='',
 )
+# bundle.reorder: experimental config
+coreconfigitem('bundle', 'reorder',
+    default='auto',
+)
 coreconfigitem('color', 'mode',
     default='auto',
 )