ID 267209 - Flare node corner sharpening causes black line artifacts

Problem summary
Flare node corner sharpening causes black line artifacts

Customer reported version
nuke.10.5v1

Customer reported platform
centos6

Steps to reproduce
1. Open Nuke
2. Create Flare node
3. Set the following:
- Corner sharpness to 1
- Angle to -45 degrees (though artifact shows at other values)
- Edge flattening to any value above 0
Result: black line artifact appears on flare 

Workaround
Modify corner sharpness to 1.001

Reproduced by support
OSX 10.11.6 
Nuke 10.5v2   
Nuke 8.0v6 
Nuke 7.0v6

Windows 8
Nuke10.5v2

Expected behaviour
No black line artifact to appear

Actual behaviour
black line artifact