I confirmed this bug in 1.5.1, not tested in snapshots
How to fix it:
1. Add cyrillic chars to font.txt (inside minecraft.jar)
2. Update LWJGL
Sorry, i forgot about file font.txt in minecraft.jar
It also must be modified.
Problem with outdated buggy LWJGL library. Version 2.8.4 has no this bug.
It is very often on slow computers.
Before fixing look at https://mojang.atlassian.net/browse/MC-2265?focusedCommentId=21484&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-21484
There is an instruction how and where to fix this bug.
Priority minor is not adequate.
Where to patch: (using MinecraftCoderPack class and methods names)
Entity.java
public void unmountEntity(Entity par1Entity)
There are two loops (on X and Z axis)
for (double dX = -1.5D; dX < 2.0D; ++dX)
for (double dZ = -1.5D; dZ < 2.0D; ++dZ)
inside these loops checked for emptiness eight blocks around player and one_level_up - see getOffsetBoundingBox(dX, 1.0D, dZ);
Block above the fence is empty, and player placed in relative coords (-1.5, 1.0, -1.5) to the north or to the west. It is exactly on wrong side of the fence.
Solution:
1. Add outer loop for (double dY = 0D; dY < 1.5D; ++dY) // optional, but i think it is normal to exit from minecart to the ground, not into air.
2. Make loops bounds smaller: for (double d = -1.0D; d < 1.1D; ++d) // important. With this values exiting is also on sibling block, but if it is something like fence - player will stand on it.
P.S.: Sorry for ugly english
Also it is duplicate of #MC-1489
All these bugs are the same. It is not font problem. It is problem with file font.txt. This file contains all accepted by minecraft chars. By default this file contains only latin chars.
For russian (may be for some other languages) there is second bug in old LWJGL library.