Traceback (most recent call last):
  File "/usr/lib/python2.6/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 753, in on_add_clicked
    self.add_source_from_line(line)
  File "/usr/lib/python2.6/dist-packages/softwareproperties/SoftwareProperties.py", line 634, in add_source_from_line
    self.set_modified_sourceslist()
  File "/usr/lib/python2.6/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 676, in set_modified_sourceslist
    SoftwareProperties.set_modified_sourceslist(self)
  File "/usr/lib/python2.6/dist-packages/softwareproperties/SoftwareProperties.py", line 425, in set_modified_sourceslist
    self.save_sourceslist()
  File "/usr/lib/python2.6/dist-packages/softwareproperties/SoftwareProperties.py", line 587, in save_sourceslist
    self.sourceslist.save()
  File "/usr/lib/python2.6/dist-packages/aptsources/sourceslist.py", line 363, in save
    files[source.file] = open(source.file, "w")
IOError: [Errno 2] No such file or directory: '/etc/apt//tmp/tmphAx5w8'