2. How we can reproduce it using the example you attached
1) Open the ViewportScene
2) Enable Single pass stereo
3) enabled Oculus SDK
4) Enter playmode
5) Click the gameview to change the viewport scale
6) Observe the game view scale incorrectly and fail to clear gfx buffer

note:
The repro above is with forward rendering,
With Deferred rendering, the gfx buffer is cleard but the scaling is still wrong.