Comment 6 for bug 953154

Unfortunately, this bug can still be found in trusty, here's the traceback:

bzr: ERROR: exceptions.TypeError: __init__() got an unexpected keyword argument 'ca_certs'

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 930, in exception_to_return_code
    return the_callable(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 1121, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 673, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.7/dist-packages/bzrlib/commands.py", line 697, in run
    return self._operation.run_simple(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 136, in run_simple
    self.cleanups, self.func, *args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/cleanup.py", line 166, in _do_with_cleanups
    result = func(*args, **kwargs)
  File "/usr/lib/python2.7/dist-packages/bzrlib/builtins.py", line 1641, in run
    branch_location)
  File "/usr/lib/python2.7/dist-packages/bzrlib/controldir.py", line 780, in open_tree_or_branch
    controldir = klass.open(location)
  File "/usr/lib/python2.7/dist-packages/bzrlib/controldir.py", line 687, in open
    t = _mod_transport.get_transport(base, possible_transports)
  File "/usr/lib/python2.7/dist-packages/bzrlib/transport/__init__.py", line 1680, in get_transport
    return get_transport_from_url(location_to_url(base), possible_transports)
  File "/usr/lib/python2.7/dist-packages/bzrlib/transport/__init__.py", line 1655, in get_transport_from_url
    transport, last_err = _try_transport_factories(url, factory_list)
  File "/usr/lib/python2.7/dist-packages/bzrlib/transport/__init__.py", line 1687, in _try_transport_factories
    return factory.get_obj()(base), None
  File "/usr/lib/python2.7/dist-packages/bzrlib/transport/http/_urllib.py", line 48, in __init__
    report_activity=self._report_activity, ca_certs=ca_certs)
TypeError: __init__() got an unexpected keyword argument 'ca_certs'

bzr 2.7.0dev1 on python 2.7.6 (Linux-3.13.0-23-generic-i686-athlon-with-
    Ubuntu-14.04-trusty)
arguments: ['/usr/bin/bzr', 'co',
    'https+webdav://xxx']
plugins: bash_completion[2.7.0dev1], changelog_merge[2.7.0dev1],
    grep[2.7.0dev1], launchpad[2.7.0dev1], netrc_credential_store[2.7.0dev1],
    news_merge[2.7.0dev1], po_merge[2.7.0dev1], weave_fmt[2.7.0dev1],
    webdav[1.12.2]
encoding: 'utf-8', fsenc: 'UTF-8', lang: 'de_DE.UTF-8'