**System Information**
Win10Home with Ryzen 8-core 1700 & Nvidia GTX 1060
**Blender Version**
Broken: recently 2.79rc, 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
{F2340228}