Update manager pops up an empty window.

[Alistair Buxton]

To reproduce, start software updated from any menu, or from the shell "update-manager", or simply wait for it to pop up on it's own (which seems to happen roughly every two hours.)

Expected result: you see available updates.

Actual result: You see an empty window.

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: update-manager 1:0.194.1
Uname: Linux 3.11.0-031100-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
Date: Thu Dec 19 11:42:16 2013
GsettingsChanges:
 b'com.ubuntu.update-manager' b'first-run' b'false'
 b'com.ubuntu.update-manager' b'launch-time' b'1387453157'
 b'com.ubuntu.update-manager' b'show-details' b'true'
 b'com.ubuntu.update-manager' b'window-height' b'200'
 b'com.ubuntu.update-manager' b'window-width' b'200'
InstallationDate: Installed on 2013-08-27 (113 days ago)
InstallationMedia: Xubuntu 13.10 "Saucy Salamander" - Alpha amd64 (20130827)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: update-manager
UpgradeStatus: No upgrade log present (probably fresh install)