Upon having a completely still WitherSkull achieved by,
/summon WitherSkull ~ ~ ~ {direction:[0.0,0.0,0.0]}
You will have a still wither skull, not a huge problem, but upon setting up some commandblocks to do the following,
/tp @e[type=WitherSkull] @p
/tp @e[type=WitherSkull] ~ ~1.4 ~
On a redstone clock, a fast one preferably, now I was using a fill clock which is essentially instant but if you'd rather use something different do as you please, now the command will simply ways teleport the WitherSkull to your heads location and what I've noticed is not one but three things, one the head is facing in the opposite direction facing backwards, two it has an inverted y axis like the chicken used to, and third if you move around no matter how fast your clock is it will never actually keep up, only occasionally pop near the head.
Is this still an issue in the current Minecraft Snapshot 15w47c or later? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.