[MC-120460] Alleged god mode by going through a nether portal while not sending the teleport confirm packet

I have not attempted to reproduce this, but with some of the other recent discussion regarding the teleport confirm packet I was reminded of this.

Apparently, if you don't send a teleport confirm packet but pass through a portal, you get put into a weird state where you're invincible but can still attack. This was discussed on #mcdevs in IRC a few months ago (log, CTRL+F Guest72257). Here's the highlights:

2017-06-05 22:46:20 Guest72257 Okay so 
2017-06-05 22:46:29 Guest72257 if you go through a portal
2017-06-05 22:46:34 Guest72257 without sending CPacketConfirmTeleport
2017-06-05 22:46:38 Guest72257 it lets you go
2017-06-05 22:46:42 Guest72257 and then you're invincibl
2017-06-05 22:46:46 Guest72257 invincbile
2017-06-05 22:46:50 Guest72257 when you reach the other side
2017-06-05 22:46:56 Guest72257 nobody can damage you

and:

2017-06-05 22:51:18 Guest72257 I can attack
2017-06-05 22:51:21 Guest72257 I can also pick up shit
2017-06-05 22:51:38 Hafydd Guest72257: oh. Do other players get damaged and see the items disappear?
2017-06-05 22:51:43 Guest72257 yep
2017-06-05 22:51:46 Hafydd Interesting.
2017-06-05 22:51:53 Guest72257 I also found out
2017-06-05 22:51:56 Guest72257 u can ride a boat
2017-06-05 22:52:01 Guest72257 when u get it
2017-06-05 22:52:04 Guest72257 the invinc
2017-06-05 22:52:05 Guest72257 then
2017-06-05 22:52:07 Guest72257 you can move
2017-06-05 22:52:10 Guest72257 in the boat

Again, I haven't tried to reproduce this yet.