When updating a world from the 1.7 format to the 1.8 format, maps in item frames become rotated twice as much as they should be.

This is closely related to bug MC-45892

This is likely related to the 1.8 feature of being able to rotate items in item frames by 45 degrees instead of 90. This requires multiplying ItemRotation by 2 for each item frame when updating it from 1.7 to 1.8.
However, maps in item frames still rotate by 90 degrees for every ItemRotation, so they become rotated twice as much as they should be.

Some possible ways to fix this:

1. When updating item frames from 1.7 to 1.8, check if the item contained is a map. If so, do nothing. Else, multiply ItemRotation by 2.
When a player rotates an item frame containing a map in the future, keep ItemRotation in the range 0-3.

2. Redefine ItemRotation for item frames containing maps, so that they are always one of

.

Steps to reproduce:

1. Load a world in 1.7.10
2. Get an item frame and a map.
3. Place the item frame on a wall and place the map in it.
4. Right click the item frame to rotate the map once.
5. Notice how the map has rotated 90 degrees
6. Close Minecraft.
7. Load the same world in 1.8
8. Notice how the map is now rotated by 180 degrees.