* DistUpgrade/DistUpgradeViewNonInteractive.py:
  - use getWithDefault() for "NonInteractive","ForceOverwrite"
    (thanks to Free Ekanayaka)
* UpdateManager/Core/MyCache.py:
  - detect dirty dpkg journal and enter recovery mode in this
    case (thanks to Maco for reporting)
* DistUpgrade/DistUpgrade.cfg:
  - remove kvm-source on upgrade
* debian/update-manager-core.links:
  - use "91-release-upgrade" instead of "91-release_upgrade" to
    make run-parts happy
* fix FTBFS