Confirmed in 15w32c, video: http://youtu.be/YSazZeAvbOw
Well, I commented there, and nothing was done... I thought nobody would care about it anymore, since no mod commented after me, and the issue was marked as resolved, and it wasn't resolved.
Was going to post this but then found this issue.
It happens because all the arrows have the same metadata AND id.
Same thing happens to potions and enchanted books, but since they aren't stackable, it doesn't change anything to the item.
It should delete the item, just like any other blocks.
Here's a video I recorded: https://youtu.be/iOde9T8C4ns
Still happening on 15w31c
Sorry, I didn't see his tweet, since I don't look EVERY TWEET HE DOES.
Also, it's not better... D:
I noticed that right after I commented... Sorry