The spawn eggs look white when I give it to mobs.

When I give ordinary spawn eggs (such as pig spawn egg or spider spawn egg) to mobs which can pick up items the spawn eggs turn white (at least it is rendered white, the default texture of a spawn egg)
How to reproduce :
1. Spawn a Zombie or Skeleton which can pick up items.
2. Drop any spawn egg to it.
3. If it holds the item, it turns white.