Copy.com back-end errors

I have tried to use duplicity to back up to Copy.com but got the following errors

Traceback (most recent call last):
  File "/usr/bin/duplicity", line 1500, in <module>
    with_tempdir(main)
  File "/usr/bin/duplicity", line 1494, in with_tempdir
    fn()
  File "/usr/bin/duplicity", line 1327, in main
    action = commandline.ProcessCommandLine(sys.argv[1:])
  File "/usr/lib/python2.7/site-packages/duplicity/commandline.py", line 1055, in ProcessCommandLine
    backup, local_pathname = set_backend(args[0], args[1])
  File "/usr/lib/python2.7/site-packages/duplicity/commandline.py", line 948, in set_backend
    globals.backend = backend.get_backend(bend)
  File "/usr/lib/python2.7/site-packages/duplicity/backend.py", line 221, in get_backend
    obj = get_backend_object(url_string)
  File "/usr/lib/python2.7/site-packages/duplicity/backend.py", line 207, in get_backend_object
    return factory(pu)
  File "/usr/lib/python2.7/site-packages/duplicity/backends/copycombackend.py", line 262, in __init__
    self.copy = CoPyCloud(parsed_url.username, self.get_password())
  File "/usr/lib/python2.7/site-packages/duplicity/backends/copycombackend.py", line 54, in __init__
    self.DEFAULT_HEADERS['X-Authorization'] = res['auth_token'].encode('ascii', 'ignore')
TypeError: string indices must be integers, not str

Duplicity 0.7.01
Python 2.7.9
Archlinux x64