Steps to reproduce:
1. Download and open the attached project
2. Enter Play mode
3. Exit Play mode

Expected result: nothing happens
Actual result: Lighting is rebaked for all the static objects in the scene, even though "Auto Generate" is not checked

Reproduced on 2017.1.0b3
Not reproduced on 5.6.0f2

Notes:
-No actual new Lighting data is created, but the process still takes as long and uses the same resources as it would if you manually baked it
-This does not happen when there are no static objects in the scene
-Also rebaked on Project load