Spiders randomly spin in circles when not tracking player

Spiders randomly spin in circles when not tracking player

What I expected to happen was...:
Spiders walking as normal
 
What actually happened was...:
Spider would walk around a bit then start spinning in circles
 
Steps to Reproduce:
1. Find a spider or use a spawn egg to spawn a bunch in.
2. Watch the spider(s)
3. Notice that they will spin in circles after a few moments.
 

This only appears to affect spiders, no other mobs.

It seems to happen most when a spider comes up on the edge of a block.

I am playing on a realms server, but I was also able to reproduce the issue in a normal survival world as per the video below.

 

Skip to 30 seconds in on the video.

Video of this issue

 (Sorry for the lag, my PC is no monster )

Thanks!

Micah