Steps to reproduce:
1. open users attached project
2. open SceneB
3. add SceneA to hierarchy
4. build lightmap

Result: Builds lightmap but does not apply it to the scene

5. open SceneA first
6. add SceneB to hierarchy
4. build lightmap

Result: Expected behaviour scene is light by red light

Notes:
- Reproduced on: 2017.1.0a3, 5.6.0f1
- Regression introduced with: 5.6.0b6
- Doesn't occur in 5.6.0b3