Code review comment for lp:~savoirfairelinux-openerp/knowledge-addons/cmis

I got a stacktrace instead of an error message when testing the connection:

Server Traceback (most recent call last):
  File "/home/max/openerp/cmis/bzr/web/addons/web/session.py", line 89, in send
    return openerp.netsvc.dispatch_rpc(service_name, method, args)
  File "/opt/openerp/7.0/server/openerp/netsvc.py", line 296, in dispatch_rpc
    result = ExportService.getService(service_name).dispatch(method, params)
  File "/opt/openerp/7.0/server/openerp/service/web_services.py", line 626, in dispatch
    res = fn(db, uid, *params)
  File "/opt/openerp/7.0/server/openerp/osv/osv.py", line 190, in execute_kw
    return self.execute(db, uid, obj, method, *args, **kw or {})
  File "/opt/openerp/7.0/server/openerp/osv/osv.py", line 132, in wrapper
    return f(self, dbname, *args, **kwargs)
  File "/opt/openerp/7.0/server/openerp/osv/osv.py", line 199, in execute
    res = self.execute_cr(cr, uid, obj, method, *args, **kw)
  File "/opt/openerp/7.0/server/openerp/osv/osv.py", line 187, in execute_cr
    return getattr(object, method)(cr, uid, *args, **kw)
  File "/home/max/openerp/cmis/bzr/knowledge/cmis/cmis_model.py", line 68, in check_directory_of_write
    repo = client.defaultRepository
  File "/home/max/openerp/cmis/git/openerp/tools/eggs/cmislib-0.5.1-py2.7.egg/cmislib/model.py", line 179, in getDefaultRepository
    doc = self.get(self.repositoryUrl, **self.extArgs)
  File "/home/max/openerp/cmis/git/openerp/tools/eggs/cmislib-0.5.1-py2.7.egg/cmislib/model.py", line 206, in get
    **kwargs)
  File "/home/max/openerp/cmis/git/openerp/tools/eggs/cmislib-0.5.1-py2.7.egg/cmislib/net.py", line 145, in get
    return opener.open(request)
  File "/usr/lib/python2.7/urllib2.py", line 404, in open
    response = self._open(req, data)
  File "/usr/lib/python2.7/urllib2.py", line 422, in _open
    '_open', req)
  File "/usr/lib/python2.7/urllib2.py", line 382, in _call_chain
    result = func(*args)
  File "/usr/lib/python2.7/urllib2.py", line 1214, in http_open
    return self.do_open(httplib.HTTPConnection, req)
  File "/usr/lib/python2.7/urllib2.py", line 1184, in do_open
    raise URLError(err)
URLError: <urlopen error [Errno 111] Connexion refusée>