Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/UpdateManager/UpdateManager.py", line 332, in install_column_view_func
    to_install = pkg.marked_install or pkg.marked_upgrade
  File "/usr/lib/python2.7/dist-packages/apt/package.py", line 953, in marked_install
    return self._pcache._depcache.marked_install(self._pkg)
SystemError: E:Malformed line 56 in source list /etc/apt/sources.list (dist parse), E:The list of sources could not be read.