I have a server that checks "stat.deaths" and "stat.leaveGame" in the world\stats*.json files. I noticed, that after playing an hour or two, "stat.leaveGame" is set to 1, without the player leaving. Not sure how to reproduce, but I know it is happening 😉
Attaching the latest example.
Is this still an issue in the current Minecraft Snapshot 15w49b or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.