Steps to reproduce:
1. Open attached project
2. Open the test scene
3. Press Play
4. Press the "Run test button"
5. Observe the rendered image in the Game window

Note: only the game view camera appears to be mirrored vertically, camera preview window, "ExampleTexture" does not seem to be affected by this issue.
(Video attached)

Expected result: The rendered image should not be mirrored

Reproduced in: 2017.1.0a6, 2017.1.0a4, 5.6.0f3, 5.6.0f2, 5.6.0b11, 5.6.0b1, 5.6.0a2, 5.6.0a1
Not reproduced in: 5.5.3f1, 5.5.2f1, 5.5.0b2, 5.5.0b9

Regression since: 5.6.0a1