System Information
Operating system: macOS Mojave 10.14.1 (18B75)
Graphics card: Radeon Pro Vega 64 16368 MB

Blender Version
Broken: 2.80, 2018-12-01, 8c620c8e2b3
Worked: 2.79b

1: Add Subdivision modifier to a connected series of edges.
2: Add Skin modifier.
➔ Mangled Skin modifier result.