--- a/mercurial/debugcommands.py	Sat May 13 17:53:55 2017 +0900
+++ b/mercurial/debugcommands.py	Sat Jan 09 23:07:20 2016 +0900
@@ -51,6 +51,7 @@
     policy,
     pvec,
     pycompat,
+    registrar,
     repair,
     revlog,
     revset,
@@ -72,7 +73,7 @@
 
 # We reuse the command table from commands because it is easier than
 # teaching dispatch about multiple tables.
-command = cmdutil.command(commands.table)
+command = registrar.command(commands.table)
 
 @command('debugancestor', [], _('[INDEX] REV1 REV2'), optionalrepo=True)
 def debugancestor(ui, repo, *args):