Connection timed out

I'm trying to branch a launchpad project. So far to no avail:

$ bzr branch lp:pyaws
bzr: ERROR: socket.error: (110, 'Connection timed out')

Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 893, in run_bzr_catch_errors
    return run_bzr(argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 839, in run_bzr
    ret = run(*run_argv)
  File "/usr/lib/python2.5/site-packages/bzrlib/commands.py", line 539, in run_argv_aliases
    return self.run(**all_cmd_args)
  File "/usr/lib/python2.5/site-packages/bzrlib/builtins.py", line 953, in run
    from_location)
  File "/usr/lib/python2.5/site-packages/bzrlib/bzrdir.py", line 888, in open_tree_or_branch
    bzrdir = klass.open(location)
  File "/usr/lib/python2.5/site-packages/bzrlib/bzrdir.py", line 765, in open
    t = get_transport(base, possible_transports=possible_transports)
  File "/usr/lib/python2.5/site-packages/bzrlib/lazy_import.py", line 125, in __call__
    return obj(*args, **kwargs)
  File "/usr/lib/python2.5/site-packages/bzrlib/transport/__init__.py", line 1554, in get_transport
    base = directories.dereference(base)
  File "/usr/lib/python2.5/site-packages/bzrlib/directory_service.py", line 58, in dereference
    return service().look_up(name, url)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad/lp_directory.py", line 60, in look_up
    return self._resolve(url)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad/lp_directory.py", line 76, in _resolve
    result = resolve.submit(service)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad/lp_registration.py", line 182, in submit
    self._authenticated)
  File "/usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad/lp_registration.py", line 147, in send_request
    result = method(*method_params)
  File "/usr/lib/python2.5/xmlrpclib.py", line 1147, in __call__
    return self.__send(self.__name, args)
  File "/usr/lib/python2.5/xmlrpclib.py", line 1437, in __request
    verbose=self.__verbose
  File "/usr/lib/python2.5/xmlrpclib.py", line 1183, in request
    self.send_content(h, request_body)
  File "/usr/lib/python2.5/xmlrpclib.py", line 1297, in send_content
    connection.endheaders()
  File "/usr/lib/python2.5/httplib.py", line 860, in endheaders
    self._send_output()
  File "/usr/lib/python2.5/httplib.py", line 732, in _send_output
    self.send(msg)
  File "/usr/lib/python2.5/httplib.py", line 699, in send
    self.connect()
  File "/usr/lib/python2.5/httplib.py", line 1134, in connect
    sock.connect((self.host, self.port))
  File "<string>", line 1, in connect
error: (110, 'Connection timed out')

bzr 1.10 on python 2.5.2 (linux2)
arguments: ['/usr/bin/bzr', 'branch', 'lp:pyaws']
encoding: 'UTF-8', fsenc: 'UTF-8', lang: 'de_DE.UTF-8'
plugins:
  avahi /usr/lib/python2.5/site-packages/bzrlib/plugins/avahi [0.3dev]
  bzrtools /usr/lib/python2.5/site-packages/bzrlib/plugins/bzrtools [1.10]
  dbus /usr/lib/python2.5/site-packages/bzrlib/plugins/dbus [unknown]
  email /usr/lib/python2.5/site-packages/bzrlib/plugins/email [unknown]
  gtk /usr/lib/python2.5/site-packages/bzrlib/plugins/gtk [0.95.0.final.1]
  launchpad /usr/lib/python2.5/site-packages/bzrlib/plugins/launchpad [unknown]
  rebase /usr/lib/python2.5/site-packages/bzrlib/plugins/rebase [0.3]
  svn /usr/lib/python2.5/site-packages/bzrlib/plugins/svn [0.4.16]
  xmloutput /usr/lib/python2.5/site-packages/bzrlib/plugins/xmloutput [0.8]
*** Bazaar has encountered an internal error.
    Please report a bug at https://bugs.launchpad.net/bzr/+filebug
    including this traceback, and a description of what you
    were doing when the error occurred.

strace revelaed that bazaar hangs trying to
connect(4, {sa_family=AF_INET, sin_port=htons(443), sin_addr=inet_addr("91.189.90.218")}, 16

My computer sits behind a proxy that also handles HTTPS traffic.

Do I have to change something in the configuration?

Cheers,
Sebastian