When loading different worlds (save files), previously loaded map items remain loaded.

What I expected to happen was...:
Map items will display the appropriate content for the world.

What actually happened was...:
The first map item of a given ID I open in a world carried over to worlds I open afterwards. In order to view the appropriate map contents, Minecraft must be restarted. The map data is not actually copied to the second world, but appears on the screen as though it was.

Steps to Reproduce:
1. View the first map created in a world (save, not dimension. create a new one if needed)
2. Exit the world, but not Minecraft
3. Open or create a second world (save, not dimension), and open the first map in that world. the map from the first world will be displayed instead, same with the 2nd, 3rd ... 9000th map of a world. I used higher numbers for pictures in maps.
4. Maps that were not loaded in the first world, but were loaded in the first will generate as normal, but that bug will carry over to the first and any future worlds
5. restart Minecraft, it will clear the bug. The bug will occur again if you open a second world without restarting. Not tested with servers.