The bug

When ocelots chase chickens or when wolves chase skeletons or sheep they jump towards their target without testing if they can land where they are jumping to.

Reproduction steps

1. Build the setup as shown in the attachment below: setup.png (2 blocks with 3 blocks of air in between)
2. Summon a chicken or sheep on the diamond block, and an ocelot or a wolf on the emerald block.
   Sometimes the ocelot or wolf jumps into the gap between the blocks

The reason

The following is based on a decompiled version of Minecraft 1.10 using MCP 9.30.

This happens probably because the method net.minecraft.entity.ai.EntityAILeapAtTarget.shouldExecute() does not test if at the position where the mob is supposed to leap to is a block.