Ridable Entities when motion tag is applied is sent below bedrock

When command block applies /entitydata @e[type=Pig] {Motion:[0.0,0.5,0.0]} to a pig and the player rides the pig, the player and pig are sent below bedrock and suffocate in bedrock with pig, this applies to survival and creative mode

EDIT: This also seems to apply to horses and Rideable minecarts