diff -r 149109c96904 -r c4a0480d1951 mercurial/configitems.py
--- a/mercurial/configitems.py	Wed Oct 04 18:51:21 2017 -0700
+++ b/mercurial/configitems.py	Mon Oct 16 18:58:16 2017 +0200
@@ -181,6 +181,8 @@
 )
 coreconfigitem('commands', 'update.check',
     default=None,
+    # Deprecated, remove after 4.4 release
+    alias=[('experimental', 'updatecheck')]
 )
 coreconfigitem('commands', 'update.requiredest',
     default=False,
@@ -412,10 +414,6 @@
 coreconfigitem('experimental', 'treemanifest',
     default=False,
 )
-# Deprecated, remove after 4.4 release
-coreconfigitem('experimental', 'updatecheck',
-    default=None,
-)
 coreconfigitem('extensions', '.*',
     default=None,
     generic=True,