To reproduce:
1. Open attached Unity project "tests.zip"
2. Open "Test 2" scene
3. Observe objects in the scene view
4. Create a new scene in the Project window
5. Observe objects in the scene again

Expected result: the objects should maintain either lighter or darker appearance, creating a scene should not impact their brightness
Actual result: Objects get lighter when a new scene is created

Note: switching to another scene and going back to the original "Test 2" scene will make the objects darker again

Reproduced on: 5.5.4p1, 5.6.2f1, 2017.1.0f1, 2017.2.0b1