Comment 3 for bug 1464330

Problem is in /usr/lib/python3/dist-packages/DistUpgrade/DistUpgradeFetcherKDE.py:

Possible fix is to change the runDistUpgrader function as follows:
    def runDistUpgrader(self):
        inhibit_sleep()
        args = [self.script, "--frontend=DistUpgradeViewKDE"] + self.run_options
        # now run it with sudo
        if os.getuid() != 0:
            os.execv("/usr/bin/kdesudo", ["kdesudo"] + args)
        else:
            os.execv(self.script, args)
        # we shouldn't come to this point, but if we do, undo our
        # inhibit sleep
        allow_sleep()