show extensions loaded on traceback

mercurial/dispatch.py

@@ -146,6 +146,8 b' def _runcatch(ui, args):'
         ui.warn(_("** or [e-mail]\n"))
         ui.warn(_("** Mercurial Distributed SCM (version %s)\n")
                % version.get_version())
+        ui.warn(_("** Extensions loaded: %s\n")
+               % ", ".join([x[0] for x in extensions.extensions()]))
         raise
 
     return -1