Danmama

Yeah, duplicated. 

Tried searching for specific words connected to the issue, but couldn't find any. Sorry. 

I was trying to make a trading hall, as the old designs. Since this is a new placed rails, I just can't.
Also, one mistake and you can't service your existing rails (after world upgrade)

Same goes for sword, enchanted with book with curse of binding (anvil) - the end result is without it.

I'm not sure if and how this is connected but this is my experience, after upgraded to latest snapshot (pre-2):

Bug 4:

• Player is insta-killed by suffocation damage, when using portal in either direction with Render distance 32 chunks.
  It takes about a minute to unload the world, before the "Downloading terrain" message appears and loads the other dimension. I have noticed, that during that time my hard disk is used 100%, which is SSD of type M.2 (really fast).

• My save game is 289MB, at the time of writing, and I have almost no constructions in the Nether, therefore most of the unloading time comes from the Overworld.
  (Unloading - the time when your screen goes to Netherrack texture when using portal, but hasn't displayed the "downloading terrain" message yet.)

For test purposes, I have reduced the render distance, down to 2 and all went well in any direction (Nether<=>Overworld).

After player is killed, all items are lost (***), instead of dropped on the ground.
==================================================================
Here, at some point of writing this, I have noticed, that I have Java update notification.
After updating to 1.8.0-73_64bit, I have managed to use the nether portal as intended (even with Render distance 32). (No idea if it's related or not, but unloading time has reduced to "non-existing".)

• • • - in one of my testing runs, I have managed to go from Nether => Overworld, but without any items, for 2 seconds.
      Then I was rubber-banded back to portal, with all my items back.
      I guess, that the game takes at least 1-tick to load your items, after using portal (load the dimension). I have a few automated redstone contraptions, with loads of mobs (400+), that sometimes make the game ticks run slower when loading.
      My point is, that if the player is insta-killed, before the dimension loads, there are no items to be dropped, since they weren't loaded yet.

I have found a workaround.
(Snapshot 15w47c, might work for the others too)

It's not perfect, and requires some "trial and error", but eventually I managed to get my Villagers into minecarts.

The setup:
I have a villager breeder, where the output of new villagers is a water stream to temporary holding cell.
It is built above my made-up village (few doors + 1 villager, underground), and because of that, durring the night time, villagers are always trying to fight the current, jumping up and down, bumping into eachother and trying to make it back to village center (to hide from zombies).

The temporary holding cell represents of just one block drop, where the output water streem ends, so i can lay a track on it, without being washed away by the water (rail, ending into a solid block).
The rest is encased into glass blocks (for visibility), leaving 1x1 block space, where the rails are heading.
Adult villagers will be encased and will not suffer any damage, during transportation, but if you end up with baby villagers - they might escape thru the hole.
Anyhow..

The "broken mechanics":
1) It has to be night time, so villagers will be willing to "go home".
2) Reach with empty bucket and take out the last water streem (tricky, while villagers are on your way and want to trade)
3) When your Holding cell is empty, you can place the minecart on the rail.
4) Put back the water streem where it was.

The result:
Eventually, a few villagers are getting pushed along on top of the minecart.
When the first villagers "lands", it king of push it away (bump it).
Then he tries to jump back into the water streem, towards "home" and being pushed back down, or the next villager drops down.
When the minecart is about 33-50% (part) pushed into the next railed block, the villager, that is dropping down (again) kind of bump it again, but then it lands into it, when the minecart moves away. (glitch into it).

It doesn't always work. (Villagers are pushing the cart away too much and then you can't place it under them or push the cart in their direction (under them).
In that case, you need to restart that last water streem, until villagers are out of the way.

Notes:
I have used a switched off powered rail. It might work with normal rail as well (not tested). If it's powered, the first bumping villager will send it on it's way.
When a villager ends up successfully into a minecart, the next dropping (jumping) down villager gives him a boost of a few (5-7) blocks along a rail track.

Good luck!