If you use the command

/tp @e[type=Witch,c=1] ~ ~1 ~

in versions before 16w21a (Not sure about 16w20a), it will, as expected, teleport the nearest witch up by one block.
However, if you use the same command in 16w21a, the result will be different;
The nearest witch will be teleported one block above the player. The witch will also teleport to the same rotation the player is looking.
This effect does not occur with command blocks.

Fix for now

Use the /tp command after an execute command directed to the entity you want teleported.

This feature was wanted for quite a while, but I'm very certain not in this form, as it breaks things completely.