I'm running Kubuntu 14.04 LTS and experienced the same problem: xdg-screensaver assumed that I use kscreensaver.
By upgrading (replacing the xdg-utils Ubuntu 14.04 package by the Upstream xdg-utils version 1.1.1) I was able to fix the problem on my computer. I suggest to backport xdg-utils 1.1.1 to Ubuntu 14.04 LTS.
I'm running Kubuntu 14.04 LTS and experienced the same problem: xdg-screensaver assumed that I use kscreensaver.
By upgrading (replacing the xdg-utils Ubuntu 14.04 package by the Upstream xdg-utils version 1.1.1) I was able to fix the problem on my computer. I suggest to backport xdg-utils 1.1.1 to Ubuntu 14.04 LTS.