List of packages updates one by one after refresh

[Roman Yepishev]

STR:

1. Get a system that needs to be updated, run update-manager
2. Hit refresh

Expected result:
List either stays intact (in case the packages requiring the update did not change) or is replaced at once.

Actual result:
The items from the original list get removed one at a time.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: update-manager 1:0.156.8
ProcVersionSignature: Ubuntu 3.2.0-18.29-generic 3.2.9
Uname: Linux 3.2.0-18-generic x86_64
ApportVersion: 1.94.1-0ubuntu2
Architecture: amd64
Date: Fri Mar 16 12:13:32 2012
GsettingsChanges:
 com.ubuntu.update-manager first-run false
 com.ubuntu.update-manager launch-time 1331892699
 com.ubuntu.update-manager show-details true
 com.ubuntu.update-manager window-height 675
 com.ubuntu.update-manager window-width 752
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha amd64 (20120225)
PackageArchitecture: all
SourcePackage: update-manager
UpgradeStatus: No upgrade log present (probably fresh install)