When you jump and place a fence post under you you will get inside the fence post

The bug

When you jump and place a fence post under you you will get inside off the fence post.

Note: This works correctly for fence gates and cobblestone walls.

Code analysis

Based on 1.11.2 decompiled using MCP 9.35 rc1

The class BlockFence is not overriding the method net.minecraft.block.Block.getCollisionBoundingBox(IBlockState, IBlockAccess, BlockPos) and therefore returns the hitbox instead of the collision box.