Expermental toggle overwrites explored chunks and erases builds.

Loaded up a seed and explored the entire starter map, planning to generate new land around that area. 

Expected result : new generation begins at edges of world where you haven't explored

What actually happens: parts of the world you have explored get changed drastically and ruins some things you might have built.

PLEASE FIX! I have a long term survival world that was ruined by this bug and I am trying to start a new one.... I don't wanna have my world change every update!