Happy new year!
I just did the manual changes you suggested, it works.
So I removed my rebuilt RPMs to install the latest nightly build. It still creates the "x2gouser" with the wrong HOME path and the x2go_sessions DB is missing. The version used was x2goserver.x86_64 0:4.1.0.0-0.0x2go1.0.git20150109.1211.heuler.el7.centos.
I've checked the HEAD for spec file in git. In x2goserver.spec, the usercreate and the DB creation seems ok. Is it possible that the nightly RPM "git20150109.1211" is not really the latest? Am I missing something?