First place an Armor Stand.
Second use the

/entitydata @e[type=ArmorStand,r=5] {Equipment:[{},{},{},{id:"minecraft:iron_chestplate"},{}]}

Third rightclick the chest plate to get 0 iron chestplates in your inventory
Fourth duplicate it with the pickblock button (middleclick) and put 1 in you armor slot
Fifth use /clear

Result: The 0 iron chestplates in your armor slot are still there.

And yes this bug report is useless because why whould anyone have 0 of an item but it's still a bug