I committed the fix to buildscripts.git and updated buildscripts.git on japsand.x2go.org (which builds & uploads the packages.)

However, for reasons explained in the linked email, I have only rebuilt the "nightly" packages with the key, not the "main" (stable release) packages yet. And the 4.1.0.0 x2goserver nightly package is very unstable.
http://lists.x2go.org/pipermail/x2go-dev/2014-December/008891.html

To any users affected by this bug, I hope to have the main packages rebuilt (and therefore fixed) ASAP.