Upgrade from 12.04 to 12.10 loops and fails with "Unable to get exclusive lock"

I'm trying to upgrade from 12.04 to 12.10 but it consistently fails in the same way.

First, the upgrade process loops (do-release-upgrade) by going through the following many times

Reading package lists... Done    

Building dependency tree... Done
Reading state information... Done
Building data structures... Done

Then it dies with "Unable to get exclusive lock".

I am not running another package manager, so this is not a duplicate of Unable to use package manager due to "exclusive lock" error.

Anybody has any ideas how to go about fixing this? I tried looking at the logs in /var/log/dist-upgrade but I couldn't find any useful error information.

I would check around, because I believe at one time you could change the repository name from say precise to quantal to produce the same effect. The process was ensure that you updated everything in your current version with repo's and then switch them and run sudo apt-get dist-upgrade.