Comment 8 for bug 1186936

I performed update-manager on 2013-July-06 .
The update-manager said "Software Updater
Not all updates can be installed

Run a partial upgrade, to install as many updates as possible.

This can be cased by:
* A previous upgrade which didn't complete
* Problems with some of the installed software
* Unofficial software packages not provided by Ubuntu
* Normal changes of a pre-releaes version of Ubuntu"

So I selected "Partial Upgrade" .

Then update-manager said "
Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade:
The package 'ubuntu-desktop' is marked for removal but it is in the removal blacklist.

This can be caused by:
* Upgrading to a pre-releae version of Ubuntu
* Running the current pre-relase version of Ubuntu
* Unofficial software packages not provided by Ubuntu

This is most likely a transient problem, please try again later ."

Then I selected "Close" .
Then do-release-upgrade crashed and https://bugs.launchpad.net/bugs/1194870 opened but I coulud not see this report .
Then searched launchpad with "saucy do-release-upgrade update-manager" .
And I found this report .