Trying to upgrade with do-release-upgrade fails

[Kirscher]

do-release-upgrade (on 13.04 to try to upgrade to 13.10) leads to following message :

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

The 2 first reason do not apply to my situation, so I have deactivated backports in sources.list , but the problem remains...

Don't know what to do to identify what is blocking the upgrade.

Any suggestion is welcome.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: ubuntu-release-upgrader-core 1:0.192.13
ProcVersionSignature: Ubuntu 3.8.0-35.50-generic 3.8.13.13
Uname: Linux 3.8.0-35-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.9.2-0ubuntu8.5
Architecture: amd64
CrashDB: ubuntu
Date: Tue Apr 29 20:36:11 2014
InstallationDate: Installed on 2013-01-31 (453 days ago)
InstallationMedia: Ubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.5)
MarkForUpload: True
PackageArchitecture: all
ProcEnviron:
 TERM=xterm
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=fr_FR.UTF-8
 SHELL=/bin/bash
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to raring on 2014-04-29 (0 days ago)

[Ubuntu Foundations Team Bug Bot (crichton)]

Reviewing the files from your upgrade attempt you seem to have enabled the xorg-edgers-ppa. This will prevent the upgrade as that PPA contains different versions of packages essential to Ubuntu. The page, https://launchpad.net/~xorg-edgers/+archive/ppa, contains details on to how to revert to the official Xorg packages. Thanks.

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[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1069133, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.
[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]