Reproduction steps:
1) In attached project, open Test scene;
2) Enter play mode;
3) Select 'Camera' object which is a child of 'Main Camera' in Hierarchy view;
4) Double click 'Render Texture' property in Inspector view;
5) Check the rendered image.

Expected results: the rendered image is supposed to have a cube image.
Actual results: the image is corrupted.

Reproduced on: 5.6.0a1, 5.6.0b5, 5.6.0b7.
Not reproduced on: 5.5.1p3, 5.5.0f3, 5.4.4p3.