Comment 12 for bug 905602

Just happened again after the app was closed and leads to dupe 911834. Since software-properties isn't opened daily by the user there is no daily report, but it certainly still crashes on two different machines after having it the first time open and then closing it.
Traceback:
 Traceback (most recent call last):
   File "/usr/lib/python2.7/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 820, in on_treeview_sources_cursor_changed
     (model, iter) = sel.get_selected()
 AttributeError: 'NoneType' object has no attribute 'get_selected'

python-gobject:
  Installed: 3.1.1-0ubuntu1
  Candidate: 3.1.1-0ubuntu1
  Version table:
 *** 3.1.1-0ubuntu1 0
        500 http://archive.ubuntu.com/ubuntu/ precise/main amd64 Packages
        100 /var/lib/dpkg/status

Dependencies in crash file say:
python-gobject 3.1.1-0ubuntu1
python-gobject-2 2.28.6-9

## Besides there is still the odd behaviour that it requests authentication on one of two machines although the versions are the same. bug 930972