System Information
Operating system and graphics card:

• Windows 8.1
• GeForce GTX 970M

Blender Version
Broken: 2.79 5bd8ac9
Date: 2017-09-11 10:43

Short description of error
The RGB Curves Node will not display a curve. I have tried loading blender files with RGB curve nodes already in them to no avail.
The RGB curve is just absent.

Exact steps for others to reproduce the error

1. Open this blender file
2. Select the cube, go into materials tab and add material
3. Click color > RGB Curves
4. Notice the distinct, terrifying lack of an RGB Curve