Shulker spawn instant position is crooked (not aligned to block grid)

This issue relates to MC-87864

Confirmed. Happens when spawning Shulker by egg, spawner or summon.

Most probably caused by the random rotation around Y-axis of any mob when spawning.

Maybe as the issue, it affects the rotation of in the monster spawner.
Link : MC-87864

Shulker is not even spawned on center of block. You can see it by doing in commandblocks in one tick:

/summon ArmorStand ~ ~ ~3
/execute @p ~ ~ ~ /summon Shulker ~ ~ ~
/tp @e[type=ArmorStand] @e[type=Shulker]
/kill @e[type=Shulker]

ArmorStand should be centered on a block, but it is not.

When there is a tick of delay between second and third command, ArmorStand will be centered to block.

Some time ago, dunno exact which version it was.

Reopening, still happens in 15w44b.

This issue appears again in 16w20a. Mod please reopened.

This issue has been fixed in 1.10-pre2.