Unable to upgrade to 14.04 from 13.10

[Thahtgie]

Software Updater fails at the "Setting new software channels" step with the following error:

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An unresolvable problem occurred while calculating the upgrade.

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

If none of this applies, then please report this bug using the command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal.

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ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: ubuntu-release-upgrader-core 1:0.205.6
ProcVersionSignature: Ubuntu 3.11.0-26.45-generic 3.11.10.12
Uname: Linux 3.11.0-26-generic x86_64
ApportVersion: 2.12.5-0ubuntu2.2
Architecture: amd64
CrashDB: ubuntu
Date: Thu Jul 24 08:38:59 2014
InstallationDate: Installed on 2013-09-30 (296 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to saucy on 2014-07-24 (0 days ago)
VarLogDistupgradeTermlog: