dispatch: disable demandimport for the --debugger option Something in Python 2.7.9 or so broke the --debugger option with ui.debugger = ipdb. I get the traceback below. There is some apparent confusion with demandimport. This should be disabled anyway for the --debugger option. The debugger must be imported right away, before any other dispatch. There's no benefit in delaying the debugger import. This patch uses the demandimport.deactivated() context manager. Traceback (most recent call last): File "/usr/lib/python2.7/dist-packages/mercurial/dispatch.py", line 121, in _runcatch debugmod = __import__(debugger) File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 115, in _demandimport return _hgextimport(_import, name, globals, locals, fromlist, level) File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 47, in _hgextimport return importfunc(name, globals, *args) File "/usr/lib/python2.7/dist-packages/ipdb/__init__.py", line 16, in <module> from ipdb.__main__ import set_trace, post_mortem, pm, run, runcall, runeval, launch_ipdb_on_exception File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 134, in _demandimport mod = _hgextimport(_origimport, name, globals, locals) File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 47, in _hgextimport return importfunc(name, globals, *args) File "/usr/lib/python2.7/dist-packages/ipdb/__main__.py", line 29, in <module> if IPython.__version__ > '0.10.2': File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 106, in __getattribute__ self._load() File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 78, in _load mod = _hgextimport(_import, head, globals, locals, None, level) File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 47, in _hgextimport return importfunc(name, globals, *args) File "/usr/lib/python2.7/dist-packages/IPython/__init__.py", line 45, in <module> from .config.loader import Config File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 132, in _demandimport return _origimport(name, globals, locals, fromlist, level) File "/usr/lib/python2.7/dist-packages/IPython/config/__init__.py", line 16, in <module> from .application import * File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 115, in _demandimport return _hgextimport(_import, name, globals, locals, fromlist, level) File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 47, in _hgextimport return importfunc(name, globals, *args) File "/usr/lib/python2.7/dist-packages/IPython/config/application.py", line 30, in <module> from IPython.external.decorator import decorator File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 134, in _demandimport mod = _hgextimport(_origimport, name, globals, locals) File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 47, in _hgextimport return importfunc(name, globals, *args) File "/usr/lib/python2.7/dist-packages/IPython/external/decorator/__init__.py", line 2, in <module> from decorator import * File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 115, in _demandimport return _hgextimport(_import, name, globals, locals, fromlist, level) File "/usr/lib/python2.7/dist-packages/mercurial/demandimport.py", line 47, in _hgextimport return importfunc(name, globals, *args) File "/usr/lib/python2.7/dist-packages/decorator.py", line 240, in <module> 'ContextManager', (_GeneratorContextManager,), dict(__call__=__call__))

--- a/mercurial/dispatch.py	Thu May 28 16:42:04 2015 -0400
+++ b/mercurial/dispatch.py	Thu May 28 16:42:21 2015 -0400
@@ -11,6 +11,7 @@
 import util, commands, hg, fancyopts, extensions, hook, error
 import cmdutil, encoding
 import ui as uimod
+import demandimport
 
 class request(object):
     def __init__(self, args, ui=None, repo=None, fin=None, fout=None,
@@ -137,10 +138,11 @@
                 # This import can be slow for fancy debuggers, so only
                 # do it when absolutely necessary, i.e. when actual
                 # debugging has been requested
-                try:
-                    debugmod = __import__(debugger)
-                except ImportError:
-                    pass # Leave debugmod = pdb
+                with demandimport.deactivated():
+                    try:
+                        debugmod = __import__(debugger)
+                    except ImportError:
+                        pass # Leave debugmod = pdb
 
             debugtrace[debugger] = debugmod.set_trace
             debugmortem[debugger] = debugmod.post_mortem