diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
--- a/mercurial/dispatch.py
+++ b/mercurial/dispatch.py
@@ -655,6 +655,10 @@ def _dispatch(req):
     rpath = _earlygetopt(["-R", "--repository", "--repo"], args)
     path, lui = _getlocal(ui, rpath)
 
+    # Side-effect of accessing is debugcommands module is guaranteed to be
+    # imported and commands.table is populated.
+    debugcommands.command
+
     # Configure extensions in phases: uisetup, extsetup, cmdtable, and
     # reposetup. Programs like TortoiseHg will call _dispatch several
     # times so we keep track of configured extensions in _loaded.
@@ -674,10 +678,6 @@ def _dispatch(req):
 
     # (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.