Can't edit or remove software sources

[Richard Ayotte]

The following message is shown when a software source is attempted to be removed. The software source is not removed successfully.

Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/softwareproperties/gtk/SoftwarePropertiesGtk.py", line 839, in on_remove_clicked
    self.backend.RemoveSource(str(source_entry))
  File "/usr/lib/python2.7/dist-packages/dbus/proxies.py", line 143, in __call__
    **keywords)
  File "/usr/lib/python2.7/dist-packages/dbus/connection.py", line 630, in call_blocking
    message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Python.AttributeError: Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/dbus/service.py", line 702, in _message_cb
    retval = candidate_method(self, *args, **keywords)
  File "/usr/lib/python2.7/dist-packages/softwareproperties/dbus/SoftwarePropertiesDBus.py", line 269, in RemoveSource
    self.remove_source(source.encode("utf-8"))
  File "/usr/lib/python2.7/dist-packages/softwareproperties/SoftwareProperties.py", line 711, in remove_source
    if source.file != apt_pkg.config.find_file("Dir::Etc::sourcelist"):
AttributeError: 'NoneType' object has no attribute 'file'

Also, any changes attempted to the source is not applied.

ProblemType: Bug
DistroRelease: Ubuntu 11.10
Package: software-properties-gtk 0.81.10
ProcVersionSignature: Ubuntu 3.0.0-12.20-generic 3.0.4
Uname: Linux 3.0.0-12-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 1.23-0ubuntu3
Architecture: amd64
Date: Wed Oct 19 07:23:22 2011
ExecutablePath: /usr/bin/software-properties-gtk
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Release amd64 (20101007.1)
InterpreterPath: /usr/bin/python2.7
PackageArchitecture: all
ProcEnviron:
 PATH=(custom, no user)
 LANG=en_CA.UTF-8
 SHELL=/bin/bash
SourcePackage: software-properties
UpgradeStatus: Upgraded to oneiric on 2011-09-23 (25 days ago)

[Robert Roth (evfool)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug #821050, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.

[Robert Roth (evfool)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug #820150, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.