Possibly related to 721313

How to reproduce:

1. Open attached project
2. Open scene Scenes/BakeLightsScene.unity
3. Go to Assets -> Bake Prefab Lightmaps
- The lightmap will be generated in the Scenes/BakeLightsScene folder
4. Attach the generated lightmap texture to the Environment1 prefab and Apply it
5. Add the lightmap texture to the 'testbundle' asset bundle in the Inspector
6. Go to Assets -> Build Asset Bundles
7. Open scene Scenes/LoadPrefabScene.unity
- Save the previous scene when prompted
8. Open the script Code/App.cs
9. Comment out line 17 (LoadEnvironmentFromResources();) and uncomment any one of the lines that follow in the Awake() message
10. Save the script and switch to Unity
11. Play the scene
- Note that one of the textures is slightly brighter than the other one

- Reproduced in Version 5.3.4f1 (fdbb5133b820)
- Blocked from testing 5.2 due to script errors
- Unity crashes in 5.4b18 when playing the scene