Mesh renderer draw shadows on terrain when painted as a tree even when the cast shadow is set to "off"

Steps to Repro:
1. Open attached project
2. Hierarchy window > select cube
3. Observe that under mesh renderer cast shadows is off and the cube is not casting a shadow on terrain
4. Select terrain > place tree tab
5. Edit tree > observe that the cube is selected as tree prefab

Actual Result:
Though the cast shadow property is set to "Off" for the cube prefab, shadows are generated on the terrain

Expected Result:
If cast shadow is set to "Off" for mesh renderer, shadows shouldn't generate if an object is painted as a tree

Occurring with:
2018.3.0a2, 2018.2.0b9, 2017.4.4f1, 2017.2.3f1 2017.1.4f1

Environment:
Windows and Mac