Traceback (most recent call last):
  File "/usr/share/software-center/softwarecenter/ui/gtk3/panes/historypane.py", line 305, in filter_row
    pkg = store.get_value(iter, self.COL_PKG)
  File "/usr/lib/python2.7/dist-packages/gi/overrides/Gtk.py", line 1196, in get_value
    return self._decode_value(treeiter, column, value)
  File "/usr/lib/python2.7/dist-packages/gi/overrides/Gtk.py", line 803, in _decode_value
    value = value.decode('UTF-8')
AttributeError: 'NoneType' object has no attribute 'decode'