[1.1.50] Crash after loading save and using undo

[Hornwitser]

Someone greifed our server by decon planning the base, I copied the autosave to my computer, changed my name to their name, loaded the save in single player and pressed Ctrl+Z many times. The game works fine for a while and then freezes for a few minutes before crashing.

Steps to reproduce
1. Change your name under other settings to Deian
2. Load the attach save in single player
3. Press Ctrl+Z several times to undo the greifing, after some time the game freeze and then crash

Alternatively instead of waiting, save the game immediately after doing the undoing and it freezes at saving the map.

[Hornwitser]

Thanks for the report, this issue is fixed for the next release.