The bug
The clearCustomName() and hasDisplayName() methods in the ItemStack class are inconsistent with getDisplayName() as they ignore the LocName NBT Tag used for custom translated displaynames.
Linked issues
relates to
Comments
pokechu22
tryashtar
Also just because the MCP mappers named them in a way that would indicate they're related doesn't mean Mojang did.
Nathan Adams
hasDisplayName()only checkingNameis what makesLocName-named items not render in italic (which is needed for e.g. villager treasure maps). I'm pretty sure that, as such, this is intended.