[apport] software-properties-gtk crashed with TypeError in remove_source()

I clicked remove from a 3rd party source, but the item did not immediately remove so i clicked it again, and then it crashed.

ProblemType: Crash
Date: Wed Feb 21 23:28:51 2007
DistroRelease: Ubuntu 7.04
ExecutablePath: /usr/bin/software-properties-gtk
InterpreterPath: /usr/bin/python2.5
Package: software-properties-gtk 0.55
ProcCmdline: /usr/bin/python /usr/bin/software-properties-gtk -n -t 50331685
ProcCwd: /home/kthompson
ProcEnviron:
 SHELL=/bin/bash
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/X11R6/bin
 LANG=en_US.UTF-8
PythonArgs: ['/usr/bin/software-properties-gtk', '-n', '-t', '50331685']
SourcePackage: software-properties
Uname: Linux trinity 2.6.20-8-generic #2 SMP Tue Feb 13 05:18:42 UTC 2007 i686 GNU/Linux