gamemode 3 and the portal

When you spectating a player, then the player goes into a portal, weird bug happens
If you press shift or change gamemode, and the player you're spectating is in the different dimension as you, you will be teleport to the same coordinate as the player, but in different dimensions.

Steps to reproduce
1. Join a server
2. /gamemode 3
3. Let the player go into a portal

(sorry for my bad English)