Thanks! I've added the following line to /usr/lib/tmpfiles.d/tmp.conf
x /tmp/.x2go-*
Hopefully that fixes it.
Then again, according to https://developers.redhat.com/blog/2016/09/20/managing-temporary-files-with-... and the general file system hierarchy, /usr/lib is not a good place to make changes.
Thankfully you should be able to move this into /etc/tmpfiles.d/x2go.conf and have that setting persist between system updates.
Do you think there should be some automated process to append that line during installation on a CentOS/RHEL system?
Yes, I should add this file to the general packaging! It's impressive how many workarounds are necessary for systemd in order for it not to break everything...
Mihai