FOSS gamedev and creative worlds

I already mentioned this in http://forum.minetest.net/viewtopic.php?id=5551 but as this keeps happening to players on our server and is a rather annoying issue I decided to make this dedicated report:

What we see is:
Player logs out (or times out) and after logging in again he spawns at some completely different coordinates from where he left. It _seems_ that this coordinates are actually matching the last saved position of another player...

Unfortunately I found no helpful/suspicious information in the debug.txt related to this problem.

We are running the latest git head of minetest and the game.

it also works after death.