Traceback (most recent call last):
  File "/usr/share/ubiquity/install.py", line 608, in <module>
    install = Install()
  File "/usr/share/ubiquity/install.py", line 75, in __init__
    self.generate_blacklist()
  File "/usr/share/ubiquity/install.py", line 261, in generate_blacklist
    difference))
  File "/usr/share/ubiquity/install.py", line 260, in <lambda>
    lambda x: not os.path.exists('/var/lib/dpkg/info/%s.prerm' % x),
  File "/usr/lib/python2.7/genericpath.py", line 18, in exists
    os.stat(path)
TypeError: must be encoded string without NULL bytes, not str