Minecart dismount position always above the minecart, even if there's space next to it

It's the official wiki, but not an official source; it's community managed, and describes the current behaviour.

(Also, this causes suffocation damage, even tho there's enough space everywhere, but above the minecart.)

Wait, what causes suffocation damage exactly?

Place a stone block 2 blocks above the minecart and observe.

Ah, I see what you mean. I also noticed that the bug does not occur if the minecart is on any type of rail, but only if the cart is on a block, ladder, etc. So as far as I can tell it won't affect ejecting mobs/players with activator rails or by breaking the cart with cactus, but only getting out of the top of a minecart elevator.

MC-3328 is about the suffocation damage

Ah, anyway, that it always places you on the minecart still doesn't seem intended.

Also the case with activator rail (MC-112329), altering ticket accordingly.
(I already thought this was the case as there's no real/big difference in shift dismounting and activator rail dismounting.)

Ok, let me try to explain what is expected, because now minecart extraction is completely not consistant, different for shift-extracting, minecart-break-extracting, activator-rail-extracting and for mob-extracting and player-extracting, shift extracting on rail is different than not on rail and so on. It was bad in 1.11, and 1.11.2 is still unexpected, inconsistant behaviour.
So...
Extracting from minecart should:
1. search for: 3-high empty place with solid block below. 3-high is for giving same behaviour for all mobs/player: from endermite to enderman.
Non solid blocks, flowers, fluids are counted as empty place, except any rails and blocks with minecart in it

2. Search for this should be in specified order:
N>S>E>W>NE>SW>NW>SE>NUp>SUp>EUp>WUp>NEUp>SWUp>NWUp>SEUp>0Up (this may pass the test if there is nothing above rail/minecart, there is wall 2-high block around, and minecart is in solid block, like in upper closed trapdoor)>NUpup>SUpup>EUpup>WUpup>NEUpup>SWUpup>NWUpup>SEUpup>0Upup

3. After all: If none of tests passed, eject in the location of minecart/activator rail.

This should make extraction reliable, consistent and easy to determine a place for any ejected entity. Moreover it would be easy to control with pistons lowerig a roof.

Search for this should be in specified order

Per this comment by @unknown, intended search order is (relative to the minecart motion)

Right, Left, Back Right, Back Left, Front Right, Front Left, Back, Front

activator rails need a rework,,,,,

they are locational,directional, they ignore non solidblocks they arent useable in 2 high rooms since it will damage you each time u get off the cart and there should be 1 rule to them: never output on the track if theres a available block( including nonsolid blocks)

Still a problem in 1.12 pre 6

Still not working correctly in 1.12 release.

in 17w45b behaviour changed, but is still broken in another way. Please update affected versions and description if you find this important:
For player it will prioritize dismounting 1 block higher next to rail with minecart than on the location. Unfortunately id does prioritize rails next to dismount location - it dismounts on the rails next to dismounting location instead of dismounting one block higher next to rails.
For mobs if no valid spot is found next to dismount location, it wont dismount 1 block higher, but on the spot.

So priority should be:
Next to rails -> one block above but not above rails -> on rail next to eject location -> on rail next to eject location 1 block higher -> on eject location on rail.
For player it is now broken:
Enywhere next to dismount location - doesn't check if its on rail or not -> enywhere next to dismount location 1 block higher - again not checking if it's on the rails or not -> on dismount location
For mobs is now broken differently than for players:
Enywhere next to dismount location - doesn't check if its on rail or not -> on dismount location