Ender Dragon glitches out when set to {NoAI:1b} mid flight.

Setting an Ender Dragon to

{NoAI:1b}

mid flight will cause the dragon the glitch out.

To reproduce:
/gamerule mobGriefing false
/summon EnderDragon ~ ~ ~
/entitydata @e[type=EnderDragon]

{NoAI:1b}

Edit: Relogging fixes it.