To reproduce:

1. Open the project, attached by tester (PreviewAwakeBug.zip)
2. Open "scene01" scene, if not open
3. Enter Play mode
4. Observe the console (Awake called one time)
5. Select PlayerPrefab in Project Window
6. Observe the console (Awake is called two more times)
7. Move the mouse between the Game window and Inspector
8. Observe the console

Expected: Awake is called only once for the object that is in the scene
Actual: Awake is called every time the inspector gains focus with the Preview window open

Reproduced in 2017.1.0b2, 2017.1.0b7, 2017.1.0b8, 2017.2.0a1
Did not reproduce in 5.5.3p2, 5.6.1p2, 2017.1.0b1
Regression introduced in 2017.1.0b2

Fixed in 2017.1.0b10