Tree prefab continuously updated on selecting "Recompute Tree" option in prefab mode.

Steps to repro:
1. Create a new project.
2. Gameobject > 3D Object > Tree.
3. Open tree game object in Prefab Mode.
4. Click on "Recompute Tree" button.

Actual Result:
Tree prefab continuously updated.

Expected Result:
Tree prefab updated once.

Reproducible in:
2020.1.0a6, 2019.3.0b5, 2019.3.0a1.

Working Fine in:
2019.2.0f1.

Environment:
Only on Windows.