Blender 2.79 build from august 13th.
I have create a normal map in 32 bit Float and saved it in Linear color space in PNG 16 bit. When i use it in Blender Render it works correctly (both Blender render and Cycles have the texture set in Linear mode, non-color does the same).
If i use the same texture in Cycles it bugs:
Here is the node setup of the normal map in Cycles:
Here is my blend file with the textures, enable Use node to switch to the Cycles shader: