* Lock parts while they're being duplicated to prevent possible race conditions with other parts changers

* This shouldn't provoke any deadlocks since the callers aren't taking any other locks beforehand

OpenSim/Region/Environment/Scenes/SceneObjectGroup.cs

@@ -1393,7 +1393,13 @@ namespace OpenSim.Region.Environment.Scenes
                 m_rootPart.ScheduleFullUpdate();
             }
             
-            List<SceneObjectPart> partList = new List<SceneObjectPart>(m_parts.Values);
+            List<SceneObjectPart> partList;
+
+            lock (m_parts)
+            {                
+                partList = new List<SceneObjectPart>(m_parts.Values);
+            }
+            
             partList.Sort(delegate(SceneObjectPart p1, SceneObjectPart p2)
                 {
                     return p1.LinkNum.CompareTo(p2.LinkNum);