You can't adjust the rotation in spawners and using /summon

When a spawner spawns mobs with custom tags using the "SpawnData" tag and the "Rotation" tag the second Double tag doesn't work. The mob is always rotated the same way.

How to reproduce
-put this in a command block

summon Pig ~ ~ ~1 {Rotation:[70.0,0.0]}

-as you can see the pig spawns with the default rotation

How to reproduce using spawners:
-Create a custom spawner, spawning rotated villagers.
-Set their health to 0 to make them despawn immediately.
-You will notice they will always look to 0 (south)