System Information
Win10Home with Ryzen 8-core 1700 & Nvidia GTX 1060
Blender Version
Broken: recently 2.79a rc, but error present for years
Worked: (optional)
Short description of error
Lines present in rendered image when using the defocus special effect node.
Exact steps for others to reproduce the error
Based on a (as simple as possible) attached .blend file with minimum amount of steps
