software-properties-gtk crashed with AttributeError in remove_source(): 'NoneType' object has no attribute 'file'

[Britt Yazel]

started when I was uninstalling software from the ubuntu software center

ProblemType: Crash
DistroRelease: Ubuntu 11.10
Package: software-properties-gtk 0.81.4
ProcVersionSignature: Ubuntu 3.0.0-7.9-generic 3.0.0
Uname: Linux 3.0.0-7-generic x86_64
Architecture: amd64
Date: Sun Jul 31 23:45:47 2011
ExecutablePath: /usr/bin/software-properties-gtk
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Release amd64 (20110427.1)
InterpreterPath: /usr/bin/python2.7
PackageArchitecture: all
ProcCmdline: /usr/bin/python /usr/bin/software-properties-gtk -n -t 33554570
ProcEnviron:
 LANGUAGE=en_CA:en
 PATH=(custom, no user)
 LANG=en_CA.UTF-8
 SHELL=/bin/bash
PythonArgs: ['/usr/bin/software-properties-gtk', '-n', '-t', '33554570']
SourcePackage: software-properties
Title: software-properties-gtk crashed with AttributeError in remove_source(): 'NoneType' object has no attribute 'file'
UpgradeStatus: Upgraded to oneiric on 2011-07-24 (8 days ago)
UserGroups:

[Apport retracing service (apport)]

Thank you for taking the time to report this crash and helping to make Ubuntu better. This particular crash has already been reported and is a duplicate of bug #820150, so 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. Please continue to report any other bugs you may find.