Assuming you have a Collab-enabled project. Assuming your first commit/publish has been done and it is the only publish done.

1. Create a 3D object
3. Create a new material.
4. Right-click and drag the newly created material to the 3D object in your scene.
5. Publish
Notice that the scene is published at the same time.
6. Rollback by chosing "Go Back to..." in Collab history.

Notice that your 3D object is still in the scene and no longer has a default material. The 3D object should also be removed, not just the material file.