Changing armor and heads on armor stands in spectator mode

A bug concerning the ability to change the armor displayed on armor stands while being in spectator mode. Spectator mode should not interfere with the environment at all.

What I expected to happen was:
You are inable to change the armor.

What happened was:
When in spectator mode, you change the armor by right clicking the armor part while holding a second armor piece in your hand.

Steps to reproduce:

• Place armor stand
• Equip armor of one type
• Place armor of other material on hotbar and select it
• Go into /gamemode 3
• Right click armor part.