Launchpadlib crashes if os.environ['HOME'] not set

If os.environ['HOME'] isn't set, Launchpadlib's login_anonymously fails:

anthony@atenea:~$ unset HOME
anthony@atenea:/home/anthony$ python
Python 2.6.6 (r266:84292, Sep 15 2010, 16:22:56)
[GCC 4.4.5] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from launchpadlib.launchpad import Launchpad
>>> Launchpad.login_anonymously('some consumer', 'https://launchpad.net/api/1.0')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/pymodules/python2.6/launchpadlib/launchpad.py", line 225, in login_anonymously
    service_root_dir) = cls._get_paths(service_root, launchpadlib_dir)
  File "/usr/lib/pymodules/python2.6/launchpadlib/launchpad.py", line 319, in _get_paths
    home_dir = os.environ['HOME']
  File "/usr/lib/python2.6/UserDict.py", line 22, in __getitem__
    raise KeyError(key)
KeyError: 'HOME'
>>>

This bites you when deploying in environments that don't ensure os.environ['HOME'] is set, as with Apache + modwsgi.