Pot corruption fix

BauSystem_Main/src/de/steamwar/bausystem/region/Region.java

@@ -20,6 +20,8 @@
 package de.steamwar.bausystem.region;
 
 import com.sk89q.worldedit.EditSession;
+import com.sk89q.worldedit.WorldEdit;
+import com.sk89q.worldedit.bukkit.BukkitWorld;
 import com.sk89q.worldedit.extent.clipboard.Clipboard;
 import de.steamwar.bausystem.BauSystem;
 import de.steamwar.bausystem.region.flags.Flag;
@@ -502,20 +504,15 @@ public class Region {
 
     public boolean undo() {
         initSessions();
-        EditSession session = null;
-        try {
-            session = undoSessions.pop();
-            if (session == null) {
-                return false;
-            }
-            session.undo(session);
-            redoSessions.push(session);
-            return true;
-        } finally {
-            if (session != null) {
-                session.flushSession();
-            }
+        EditSession session = undoSessions.pop();
+        if (session == null)
+            return false;
+
+        try (EditSession e = WorldEdit.getInstance().getEditSessionFactory().getEditSession(new BukkitWorld(Bukkit.getWorlds().get(0)), -1)) {
+            session.undo(e);
+            redoSessions.push(e);
         }
+        return true;
     }
 
     public boolean redo() {