Lead is shifted upwards or downwards based on leashed entity height

The bug

Leads are rendered shifted upwards based on the eye level of the leashed entity. This causes the lead start to be rendered too high for taller mobs like iron golems or horses.

Code analysis

Based on 1.12 decompiled using MCP 9.40 PRE 1

The method net.minecraft.client.renderer.entity.RenderLiving.renderLeash(T, double, double, double, float, float) shifts the rendering position upwards based on the leashed entity's eye level instead of only the end position, which might be partwise the cause for MC-13823.