Worldborder still moves after game is paused in singleplayer

What I expected to happen was...:
When I pause the game the Worldborder stops.

What actually happened was...:
The Worldborder kept moving

Steps to Reproduce:
1. Enter the command "/worldborder center ~ ~"
2. Enter the command "/worldborder set 1"
3. Enter the command "/worldborder set 10 10"
4. While the Border is moving, pause the game.