System Information
Operating system: macOS Mojave 10.14.5 (18F132)
Graphics card: Intel Iris Graphics 6100 1536 MB

Blender Version
Broken: 2.80
Worked: (optional)

Short description of error

Edge select color use that color in edge select mode, but in vertex select mode it blends from unselected edge color to selected color. I use light blue for unselected. It is expected that the light blue is gradiented to orange (the same orange as vertex selected color) in the screenshot below. But instead it goes to light green. This color doesn't exist in the theme at all.

Exact steps for others to reproduce the error
Look at the attached GIF. Just try other edge color and edge select color so it blends together to a different color.