If a user completes two paint holes actions on a Terrain object then hits ctrl-z to Undo. Then it will corrupt the Terrain Object and cause further paint hole actions to no behave as expected.

Repro Steps:
1. Create a Terrain Object in the scene
2. Select the paint holes tool
3. Paint holes on the Terrain
4. Paint more holes on the Terrain (Important, as the issue does not reproduce when only a single paint holes action has been done)
5. Press Ctrl-Z to undo your last paint holes action

Actual Results:
Terrain holes data is put into a bad state where further paint actions do not behave as expected. Tending to create much larger holes than expected.

Expected Results:
Holes that would get painted on the Terrain would align with the user's brush.

Reproduces on: 2020.2.0b9
Does not Reproduce on: 2020.2.0b8