Steps to reproduce:
1) Start minecraft server with extended memory sizes (java -Xmx1G -Xms1G -jar minecraft_server.jar)
2) Launch client
3) Connect to created game

Actual:
Player can't move in world: he always returns to the original starting position. Also some chunks of world not loaded.

Log with debug start is attached.

Note: this bug was reproduced after MC-3639.