KDE frontend crash during doPostUpgrade

Binary package hint: update-manager

upgrading from lucid to maverick I got a crash in the KDE frontend of DistUpgrade tool

Original exception was:
Traceback (most recent call last):
  File "/tmp/tmpd2URsC/maverick", line 7, in <module>
    sys.exit(main())
  File "/tmp/tmpd2URsC/DistUpgradeMain.py", line 158, in main
    if app.run():
  File "/tmp/tmpd2URsC/DistUpgradeController.py", line 1616, in run
    return self.fullUpgrade()
  File "/tmp/tmpd2URsC/DistUpgradeController.py", line 1603, in fullUpgrade
    self.doPostUpgrade()
  File "/tmp/tmpd2URsC/DistUpgradeController.py", line 1150, in doPostUpgrade
    self._view.confirmChanges(summary, changes, 0, actions, False)):
  File "/tmp/tmpd2URsC/DistUpgradeViewKDE.py", line 725, in confirmChanges
    downloadSize)
  File "/tmp/tmpd2URsC/DistUpgradeView.py", line 367, in confirmChanges
    apt_pkg.SizeToStr(downloadSize)
TypeError: Only understand integers and floats

running the tool a second time from where it left off successfully completed without problem