After adding cloth component on a prefab from project folder, selecting prefab in the hierarchy mesh collider keeps adding up and throws errors in the console.

To reproduce:
1. Create new unity project
2. Create cube in the hierarchy
3. Drag it to project folder to make it a prefab
4. Select the prefab in the project folder and add cloth component, notice as there is no Mesh Collider
5. Select the prefab in the hierarchy
6. Observe as the mesh collider appeared on the prefab
7. Repeat steps 4 - 5 and observe as the prefab in the hierarchy gets more and more Mesh Colliders

Expected result: mesh collider does not add up on the prefab
Actual result: mesh collider keeps adding up on the prefab

Reproduced on: 2017.3.0b1 2017.3.0b5 2018.1.0a1
Not reproduced on: 2017.2.0f3 2017.3.0a3 2017.3.0a6
|Regression introduced in: 2017.3.0a7

Notes: also reproduces on MAC.