When I was making a villager controller using /execute detect and /entitydata, whenever the villager was moving east, it wouldn't go down if i set the Y motion downwards. I went through the command, and copy-pasted it to go west. Guess what, it worked.
What I expected to happen was:
For the villager to move east and down.
What actually happened was:
The villager had no downward motion when I set the motion down.
Steps to reproduce:
1.Put this command on a 20-tick per second clock: "/entitydata @e[type=Villager] {Motion:[-0.2,-0.2,0.0]}"
2. Summon a villager in the air.
3. Watch it go east but not down.
4. Make the command go west and watch the villager move west AND down.
Problems related to modifying internal NBT tags during the lifetime of an entity are not considered bugs, they will be marked as "working as intended"