[23:40:23 ERROR]: Encountered an unexpected exception
java.util.ConcurrentModificationException
        at java.util.HashMap$HashIterator.nextEntry(HashMap.java:926) ~[?:1.7.0_51]
        at java.util.HashMap$KeyIterator.next(HashMap.java:960) ~[?:1.7.0_51]
        at net.minecraft.server.v1_7_R3.EntityTracker.updatePlayers(EntityTracker.java:152) ~[craftbukkit-beta.jar:git-Bukkit-1.7.9-R0.1-b3084jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.v(MinecraftServer.java:658) ~[craftbukkit-beta.jar:git-Bukkit-1.7.9-R0.1-b3084jnks]
        at net.minecraft.server.v1_7_R3.DedicatedServer.v(DedicatedServer.java:260) ~[craftbukkit-beta.jar:git-Bukkit-1.7.9-R0.1-b3084jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.u(MinecraftServer.java:558) ~[craftbukkit-beta.jar:git-Bukkit-1.7.9-R0.1-b3084jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.run(MinecraftServer.java:469) [craftbukkit-beta.jar:git-Bukkit-1.7.9-R0.1-b3084jnks]
        at net.minecraft.server.v1_7_R3.ThreadServerApplication.run(SourceFile:628) [craftbukkit-beta.jar:git-Bukkit-1.7.9-R0.1-b3084jnks]
[23:40:23 ERROR]: This crash report has been saved to: /home/mc/mc1.7.2/./crash-reports/crash-2014-06-17_23.40.23-server.txt