Windows 10 x64
AMD Radeon R9390X - Graphics card
AMD FX-8320 - CPU
Broken: All Blender versions
Short description of error
Adding a normal map to a model breaks the shading of the object.
Exact steps for others to reproduce the error
Press "M" to toggle (mute/unmute) the normal map in the file and watch the shading change in the 3D view window.
Here is a video I recorded showing the problem in more detail.