Repro steps:

• Sit on a horse/pig
• Teleport either yourself or the pig (I used (10, 0, 0))
• Only the selected entity is teleported, not the entire stack

Tested on Fabric 0.10.3, 0.9.6, and 0.9.2, and Forge 0.10.3, 0.9.6, and 0.9.4.
See also: #186

I'm just gonna remove this whole mechanic, no one uses it and it's dumb

maybe people would use it if it worked? i think it's a neat tradeoff to get no drop teleporting but have to manage a living mob

如果它有效，也许人们会使用它？我认为这是一个巧妙的权衡，没有掉落传送，但必须管理一个活生生的生物

oh we can use the ender pearl to get this purpose, just throw it into a area of rising bubbles, we can teleport it to any place that we want to go.