Steps to reproduce:

1) Download attached project 'Unity56StencilBug.zip' and open in Unity
2) Open scene 'MainBugger' and press Play
Note that Scene view will be solid black

Expected result: Scene should not be solid black and cube should be visible(check attached image 'Result.png')
Actual result: Scene view is completely black and cube is not visible

Reproduced with:
5.6.0p4, 5.6.2p4, 2017.1.0p1, 2017.2.0b3

Not reproduced with:
5.5.4p2, 5.6.0a1, 5.6.0f1, 5.6.0p3

Regression since:
5.6.0p4

----------------------------------------------------
Fixed in 2017.1.1p2, 2017.2.0b9, 2017.3.0a6