diff -r d1a0a64f6e16 -r 869d660b8669 mercurial/dispatch.py
--- a/mercurial/dispatch.py	Mon Nov 14 23:17:15 2016 +0000
+++ b/mercurial/dispatch.py	Wed Aug 17 21:07:38 2016 -0700
@@ -26,6 +26,7 @@
 from . import (
     cmdutil,
     commands,
+    debugcommands,
     demandimport,
     encoding,
     error,
@@ -768,6 +769,10 @@
 
     # (reposetup is handled in hg.repository)
 
+    # Side-effect of accessing is debugcommands module is guaranteed to be
+    # imported and commands.table is populated.
+    debugcommands.command
+
     addaliases(lui, commands.table)
 
     # All aliases and commands are completely defined, now.