System Information
Operating system: Windows 10
Graphics card: Nvidia GTX 1080 Ti
CPU: Intel core i7 7700-k
RAM: 64GB / 2400mhz

Blender Version
Broken: 2.8 Release Candidate
Worked: 2.79

Short description of error
When you set an object with shapekeys as a boneshape it will cause that bone to flicker whenever any bone of the armature is being translated, scaled, or rotated

Exact steps for others to reproduce the error
Create any object and add a shapekey to it, then set your object as a boneshape of any bone in the armature, and then move any bone and you will see flickering in the bone that has the object with shapekeys