$ cat /tmp/go.py
#!/usr/bin/python
from launchpadlib.launchpad import Launchpad
LP = Launchpad.login_with('rescan cloud-init', 'production', version='devel')
repo = LP.git_repositories.getByPath(path='cloud-init')
repo.rescan()

$ python /tmp/go.py
$ echo $?
0

$ python3 /tmp/go.py
Traceback (most recent call last):
  File "/tmp/go.py", line 8, in <module>
    repo.rescan()
  File "/usr/lib/python3/dist-packages/lazr/restfulclient/resource.py", line 622, in __call__
    self.resource.lp_refresh()
  File "/usr/lib/python3/dist-packages/lazr/restfulclient/resource.py", line 759, in lp_refresh
    super(Entry, self).lp_refresh(new_url, etag)
  File "/usr/lib/python3/dist-packages/lazr/restfulclient/resource.py", line 346, in lp_refresh
    representation, self.JSON_MEDIA_TYPE)
  File "/usr/lib/python3/dist-packages/wadllib/application.py", line 363, in bind
    representation_definition)
  File "/usr/lib/python3/dist-packages/wadllib/application.py", line 300, in __init__
    _make_unicode(representation))
  File "/usr/lib/python3/dist-packages/simplejson/__init__.py", line 516, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3/dist-packages/simplejson/decoder.py", line 374, in decode
    obj, end = self.raw_decode(s)
  File "/usr/lib/python3/dist-packages/simplejson/decoder.py", line 404, in raw_decode
    return self.scan_once(s, idx=_w(s, idx).end())
simplejson.scanner.JSONDecodeError: Expecting value: line 1 column 1 (char 0)