add-apt-repository fails with AttributeError: 'module' object has no attribute 'Config'

[Chris D]

add-apt-repository is failing in the RC ISO installation. If you run the utility with any valid PPA as the argument, you get the following output:

Traceback (most recent call last):
  File "/usr/bin/add-apt-repository", line 65, in <module>
    if not sp.add_source_from_line(line):
  File "/usr/lib/python2.7/dist-packages/softwareproperties/SoftwareProperties.py", line 630, in add_source_from_line
    (deb_line, file) = expand_ppa_line(line.strip(), self.distro.codename)
  File "/usr/lib/python2.7/dist-packages/softwareproperties/ppa.py", line 47, in expand_ppa_line
    sourceslistd = apt_pkg.Config.find_dir("Dir::Etc::sourceparts")
AttributeError: 'module' object has no attribute 'Config'

Running LMDE 201104 RC 64 bit ISO.