I can reproduce this using CTRL+Pick-Block in 14w30b.
Got the same crash while flying around in creative. =3
You don't need another crash log, do you?
I found that this happens when there are ungenerated chunks in the custom map near the player. I believe this might be an issue with the terrain generator.
I can confirm this still happens in 14w11b. A sitting wolf teleported about 60 chunks away and appeared, still sitting, next to me.
Reproduced. And if you use two or three dyes, it gets even crazier. =3