Linux Mint 19 Cinnamon
GeForce GTZ 1050 Ti
Broken: Blender 2.79 2017-09-11
Short description of error
Turning on Open Shading Language breaks a cycles material that uses a Normal node. The output of the shader is black.
Exact steps for others to reproduce the error
The cycles material in the attached blend file works as expected if Open Shader Langauge is unchecked in the Render panel.
The material is completely black if Open Shader Langauge is checked.
The problem appears to be with the Normal node, as feeding the Normal output of the Geometry node directly into the Emission node works whether OSL is on or off.
This has been duplicated in 2018-08-06 build of 2.79.