Error when selecting "launchpad" as command-category

Hello,
i wanted to register my Launchpad login with bazar, like it's described here: http://doc.bazaar.canonical.com/explorer/en/guide/setup.html

but when i select the command-category "launchpad", i get this error:
"
bzr: ERROR: exceptions.UnicodeEncodeError: 'ascii' codec can't encode character u'\xfc' in position 319: ordinal not in range(128)

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/bzrlib/plugins/qbzr/lib/run.py", line 255, in set_cmd_help
    self.ui.help_browser.setHtml(html_utf8.decode('utf-8'))
  File "/usr/lib/python2.7/encodings/utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xfc' in position 319: ordinal not in range(128)

bzr 2.7.0dev1 on python 2.7.8 (linux2)
arguments: ['/usr/bin/bzr', 'qrun', '--ui-mode']
encoding: 'utf-8', fsenc: 'UTF-8', lang: 'de_DE.UTF-8'
plugins:
  bash_completion /usr/lib/python2.7/dist-packages/bzrlib/plugins/bash_completion [2.7.0dev1]
  changelog_merge /usr/lib/python2.7/dist-packages/bzrlib/plugins/changelog_merge [2.7.0dev1]
  explorer /usr/lib/python2.7/dist-packages/bzrlib/plugins/explorer [1.3.0]
  grep /usr/lib/python2.7/dist-packages/bzrlib/plugins/grep [2.7.0dev1]
  launchpad /usr/lib/python2.7/dist-packages/bzrlib/plugins/launchpad [2.7.0dev1]
  netrc_credential_store /usr/lib/python2.7/dist-packages/bzrlib/plugins/netrc_credential_store [2.7.0dev1]
  news_merge /usr/lib/python2.7/dist-packages/bzrlib/plugins/news_merge [2.7.0dev1]
  po_merge /usr/lib/python2.7/dist-packages/bzrlib/plugins/po_merge [2.7.0dev1]
  qbzr /usr/lib/python2.7/dist-packages/bzrlib/plugins/qbzr [0.23.1]
  weave_fmt /usr/lib/python2.7/dist-packages/bzrlib/plugins/weave_fmt [2.7.0dev1]
"
My versions:

bzr Verison: 2.7.0dev1
Python interpreter: /usr/bin/python 2.7.8
Python standard library: /usr/lib/python2.7
Platform: Linux-3.16.0-23-generic-x86_64-with-Ubuntu-14.10-utopic
QBzr 0.23.1, bzrlib 2.7.0dev1, PyQt 4.11.2, Qt 4.8.6, Python 2.7.8
My interface language is german.