Operating system and graphics card
Debian 8 64bit, GTX 780
Broken: (example: 2.77a abf6f08, see splash screen)
Short description of error
There are black holes in reflections on the objects on some angles.
Take a look some screenshots.
Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps
Create simple scene with a cube, set smooth shading (IMPORTANT, this bug won't work on flat shading), add simple glossy material with roughness 0 (it will be easier to see these holes with low roughness), add HDR to environment. Go to render mode and watch at the surface. You will see black holes on surface. I think that it is the issue of normals interpolation, because you can add few levels of edge bevel.
But what if I don't want to add additional polygons with subdivide or bevel? Bug!