update-manager crashed with AttributeError in _on_download_changed(): 'NoneType' object has no attribute 'set_value'

[ebnf]

Left update manager running in the background for several hours, came back and it was unresponsive.

ProblemType: Crash
DistroRelease: Ubuntu 12.10
Package: update-manager 1:0.170
ProcVersionSignature: Ubuntu 3.5.0-13.14-generic 3.5.3
Uname: Linux 3.5.0-13-generic x86_64
ApportVersion: 2.5.1-0ubuntu4
Architecture: amd64
Date: Mon Sep 3 13:47:19 2012
EcryptfsInUse: Yes
ExecutablePath: /usr/bin/update-manager
GsettingsChanges:
 b'com.ubuntu.update-manager' b'first-run' b'false'
 b'com.ubuntu.update-manager' b'launch-time' b'1346684008'
 b'com.ubuntu.update-manager' b'show-details' b'true'
 b'com.ubuntu.update-manager' b'window-height' b'240'
 b'com.ubuntu.update-manager' b'window-width' b'500'
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
InterpreterPath: /usr/bin/python3.2mu
PackageArchitecture: all
ProcCmdline: /usr/bin/python3 /usr/bin/update-manager --no-update --no-focus-on-map
PythonArgs: ['/usr/bin/update-manager', '--no-update', '--no-focus-on-map']
SourcePackage: update-manager
Title: update-manager crashed with AttributeError in _on_download_changed(): 'NoneType' object has no attribute 'set_value'
Traceback:
 Traceback (most recent call last):
   File "/usr/lib/python3/dist-packages/aptdaemon/gtk3widgets.py", line 522, in _on_download_changed
     model.set_value(iter, self.COL_TEXT, text)
 AttributeError: 'NoneType' object has no attribute 'set_value'
UpgradeStatus: Upgraded to quantal on 2012-07-20 (45 days ago)
UserGroups: adm cdrom dip lpadmin plugdev sambashare sudo

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Florian Hars (hars)]

I had the "system needs reboot" open for a while, then when the next update came, it displayed the list of available updates for a moment, then became unresponsive and finally crashed.

[jesse (jesse)]

Hit as well after a reboot. Auto logged it and was greeted with the crash in the system tray.

[Filiprino (filiprino)]

Just had this error. Happened when I clicked the close button by accident (the button on the window bar).

[Craig Kempson (ckempo)]

Echoing Filiprino in #5, I've also just caused this by accidently hitting close whilst packages were being installed.

[Abdelaziz Yakout (yooozy)]

when it was installing packages I hit exit, this error happened.