Description of problem:
I'm using F12 with updates-testing enabled. Today a transmission update (https://admin.fedoraproject.org/updates/F12/FEDORA-2010-0615) confused gpk-update-viewer. When attempting to install updates I am getting an error dialog:
  Transaction error
  An unspecified transaction error has occurred. More information is available in the detailed report.
  More details:
  could not add package update for transmission-1.80-0.5.b5.fc12(x86_64)updates-testing: transmission-1.80-0.5.b5.fc12.x86_64

Version-Release number of selected component (if applicable):
gnome-packagekit-2.28.3-0.1.20091211git.fc12.x86_64
PackageKit-0.5.6-1.fc12.x86_64
PackageKit-glib-0.5.6-1.fc12.x86_64
PackageKit-yum-0.5.6-1.fc12.x86_64
yum-3.2.25-1.fc12.noarch
rpm-4.7.2-1.fc12.x86_64

How reproducible:
always

Steps to Reproduce:
1. Make sure you have a previous version of transmission installed (I have transmission-1.77-1.fc12.x86_64).
2. Try using gpk-update-viewer to update to the current version in updates-testing (transmission-1.80-0.5.b5.fc12).
  
Actual results:
Update fails with the already mentioned error.

Expected results:
Update should finish successfully.

Additional info:
Updating using "pkcon update" works fine.
Updating with plain yum works fine too:

------------------------------------------------------------
Setting up Update Process
Resolving Dependencies
--> Running transaction check
---> Package transmission-gtk.x86_64 0:1.80-0.5.b5.fc12 set to be updated
--> Processing Dependency: transmission-common for package: transmission-gtk-1.80-0.5.b5.fc12.x86_64
--> Running transaction check
---> Package transmission-common.x86_64 0:1.80-0.5.b5.fc12 set to be updated
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================
 Package                Arch      Version              Repository          Size
================================================================================
Installing:
 transmission-gtk       x86_64    1.80-0.5.b5.fc12     updates-testing    556 k
     replacing  transmission.x86_64 1.77-1.fc12

Installing for dependencies:
 transmission-common    x86_64    1.80-0.5.b5.fc12     updates-testing    369 k

Transaction Summary
================================================================================
Install       2 Package(s)
Upgrade       0 Package(s)

Total download size: 925 k
Is this ok [y/N]: y
Downloading Packages:
Setting up and reading Presto delta metadata
Processing delta metadata
Package(s) data still to download: 925 k
(1/2): transmission-common-1.80-0.5.b5.fc12.x86_64.rpm   | 369 kB     00:00     
(2/2): transmission-gtk-1.80-0.5.b5.fc12.x86_64.rpm      | 556 kB     00:00     
--------------------------------------------------------------------------------
Total                                           484 kB/s | 925 kB     00:01     
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
Warning: RPMDB has been altered since the last yum transaction.
  Installing     : transmission-common-1.80-0.5.b5.fc12.x86_64              1/3 
  Installing     : transmission-gtk-1.80-0.5.b5.fc12.x86_64                 2/3 
  Erasing        : transmission-1.77-1.fc12.x86_64                          3/3 

Installed:
  transmission-gtk.x86_64 0:1.80-0.5.b5.fc12                                    

Dependency Installed:
  transmission-common.x86_64 0:1.80-0.5.b5.fc12                                 

Replaced:
  transmission.x86_64 0:1.77-1.fc12                                             

Complete!
----------------------------------------------------------

"yum history undo" can be used to go back to the previous version of transmission to reproduce the problem with gpk-update-viewer again.