In the Minecraft 1.9 snapshots, leads tied around fence posts and animals, sometimes glitch out, causing them to stretched towards, coordinates 0 0 0.
Wandering around Minecraft 1.9, when I noticed that the lead that I attached to the fence post and animal was glitching and stretching out into the terrain, and underground. After exploring a bit, I found out that the lead was glitch stretching out to coordinates 0 0 0.