The bug
The method bbj.b(du) (16w39c) which writes the map data to a NBT compound writes the value (bbj.e) of the trackingPosition tag for the unlimitedTracking tag as well despite that tag having its own field bbj.f.
I do not know the effect this has on the gameplay.
I was hoping this bug would be fixed with yours, but it's still in MC 16w44a 😞
I will probably need to get used to it 😞(((
https://bugs.mojang.com/browse/MC-108870