Operating system: Windows 10 Pro
Graphics card: GTX 1060
2.80, Hash: 7d792976e100, Branch: blender2.7
Short description of error
In cycles some faces renders as if flat shaded, although it should be smooth shaded.
Even adding a subdivition modifier doesn't solve this problem (faces just get smaller).
Exact steps for others to reproduce the error
See attached .blend file.