Editing Software Sources through System Settings reliably crashes

software-properties-gtk crashed with SIGSEGV in g_closure_invoke()

ProblemType: Crash
DistroRelease: Ubuntu 14.10
Package: software-properties-gtk 0.94
ProcVersionSignature: Ubuntu 3.16.0-22.29-generic 3.16.4
Uname: Linux 3.16.0-22-generic x86_64
ApportVersion: 2.14.7-0ubuntu5
Architecture: amd64
CrashCounter: 1
CurrentDesktop: Unity
Date: Sun Oct 12 14:03:36 2014
ExecutablePath: /usr/bin/software-properties-gtk
InstallationDate: Installed on 2014-07-23 (81 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
InterpreterPath: /usr/bin/python3.4
PackageArchitecture: all
ProcCmdline: /usr/bin/python3 /usr/bin/software-properties-gtk
ProcEnviron:
 PATH=(custom, no user)
 LANGUAGE=en_US
 XDG_RUNTIME_DIR=<set>
 LANG=en_US.UTF-8
 SHELL=/usr/bin/zsh
SegvAnalysis:
 Segfault happened at: 0x7f12fa613850: mov (%rdi),%rax
 PC (0x7f12fa613850) ok
 source "(%rdi)" (0x00000000) not located in a known VMA region (needed readable region)!
 destination "%rax" ok
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: software-properties
StacktraceTop:
 ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
 ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
 ?? () from /usr/lib/x86_64-linux-gnu/libgtk-3.so.0
 g_closure_invoke () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
 ?? () from /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
Title: software-properties-gtk crashed with SIGSEGV in g_closure_invoke()
UpgradeStatus: Upgraded to utopic on 2014-10-12 (0 days ago)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo