Cape animation broken while walking

YOU NEED A CAPE TO TEST THIS BUG

• Join any Minecraft world
• Toggle perspective mode, so you can see your cape
• Now start walking with sprint and press W+A or W+D 
• Move your mouse in the direction you're walking (it should look like you're walking in circles)
• Observe how weirdly the cape behaves

Unfortunately, I was unable to attach a video, since it's size way too high, so consider downloading from this source:

• MEGA: clickable link