Off-hand map with enchantment glow when holding enchanted item

The off-hand minimap turned the color purple (This does not work with other hand)

What I expected to happen was...:
Nothing out of the ordinary

What actually happened was...:
The off-hand minimap turned dark purple

Steps to Reproduce:
1. Create map
2. Put map in off-hand slot
3. Effect yourself with invisibility
4. Hold any item with enchant glistening effect

This happens with:
Every 1.9 snapshot version