Polymer: Flickering line on interpolated weapon sprites
This was introduced with f6ee47e2 and involves weapons sprite interpolation in Polymer.
In short, every time the weapon sprites is moved (standard movebob) then a flickering line of pixels appears over the gun. It only occurs if r_rotatespriteinterp is set to 1 or higher.
On closer inspection, this appears to be the bottom line of pixels being rendered at the top:
For more information, see the following Duke4 thread:
https://forums.duke4.net/topic/11680-flickering-line-on-weapon-in-polymer/