In 1.9, since it's compatible on the server now, you are able to push people. This can lead to player killing. Way to disable it? I don't seem to know, but there might be a way. ;p
It's 1.9 compatible, but there's no aspects of 1.9 on the server atm. So no player pushing or crappy pvp.
The server is still 1.8 so pushing should not yet work? No 1.9 mechanics should work. Has this happened?