Nether Portals are broken in 15w40b!!!

My server has recently had to be downgraded from 15w41b to 15w40b because going through a nether portal in survival mode will get you to your overworld coords. Example: you get through nether portal from overworld at 15 50 15. In the Nether, you spawn in 15 50 15 when you are supposed to spawn at somewhere else. This is a bug, and please get it fixed.