If you go through a nether portal, then go quickly go out then back in the warp effect will keep playing forever. This is the exact same effect as with MC-180. 

What I expected to happen was...:
That the nether portal would teleport me to the nether.

What actually happened was...:
The nether portal kept playing the animation forever.

Steps to Reproduce:
1. Build a nether portal
2. Go through it
3. Step out of the portal then step back in quickly

4. Notice how the animation plays forever until you step out of the portal

Link has been removed because this report is a duplicate