[PATCH] dispatch: disable demandimport when invoking the debugger

[Jordi Gutiérrez Hermoso]

# HG changeset patch
# User Jordi Gutiérrez Hermoso <jordigh at octave.org>
# Date 1441891810 14400
#      Thu Sep 10 09:30:10 2015 -0400
# Node ID 4db58521c46a1202b058a1a5c1e26d491c108188
# Parent  ea489d94e1dc1fc3dc1dcbef1c86c18c49605ed1
dispatch: disable demandimport when invoking the debugger

Turns out that demandimport confuses pudb, which does some pretty
complicated imports. I think it's reasonable to disable demandimport
here.

diff --git a/mercurial/dispatch.py b/mercurial/dispatch.py
--- a/mercurial/dispatch.py
+++ b/mercurial/dispatch.py
@@ -181,8 +181,8 @@ def _runcatch(req):
                     debugtrace[debugger] == debugtrace['pdb']):
                     ui.warn(_("%s debugger specified "
                               "but its module was not found\n") % debugger)
-
-                debugtrace[debugger]()
+                with demandimport.disabled():
+                    debugtrace[debugger]()
             try:
                 return _dispatch(req)
             finally: