Mobs can drop tools with 0 durability

Hello,

Recently, I managed to build up a massive mob grinder in the middle of the ocean recently to acquire more experience and mob drops. Going through my chests, I was occasionally able to find items that were dropped by mobs such as swords, shovels, bows, and even tridents (but never armor) that had 0 durability (as shown with advanced tooltips on). I did some testing to make sure that this was not intended, and discovered that when you use a tool (without unbreaking) that has 1 durability, it instantly breaks rather than going to 0 durability, meaning that you can only obtain such tools from mobs. I decided to give these tools a test of my own. Sure enough, when I used them, they broke instantly. There's no severely game-breaking aspect about this, and it is not an urgent glitch to fix, but it can be confusing sometimes. This works in all versions of Minecraft.