java.lang.IllegalArgumentException: Not a DataFolder: C:\Users\Lu\Documents\NetBeansPlatform\main\nbbuild\netbeans\extra\jython-2.5.1\Lib\test\$test@b49bf89d:1b6a728 (was a org.openide.loaders.DefaultDataObject) (file is folder? false)
   at org.openide.loaders.DataFolder.findFolder(DataFolder.java:545)
   at org.netbeans.modules.python.project.ui.PackageViewChildren.createNodes(PackageViewChildren.java:164)
   at org.netbeans.modules.python.project.ui.PackageViewChildren.createNodes(PackageViewChildren.java:126)
   at org.openide.nodes.Children$Keys$KE.nodes(Children.java:1662)
   at org.openide.nodes.ChildrenArray.nodesFor(ChildrenArray.java:149)
   at org.openide.nodes.EntrySupportDefault$Info.nodes(EntrySupportDefault.java:805)
   at org.openide.nodes.EntrySupportDefault.updateAdd(EntrySupportDefault.java:441)
   at org.openide.nodes.EntrySupportDefault.setEntries(EntrySupportDefault.java:295)
   at org.openide.nodes.EntrySupport.setEntries(EntrySupport.java:83)
   at org.openide.nodes.Children$Keys$2.run(Children.java:1556)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation$1Exec.run(DefaultMutexImplementation.java:1016)
   at org.openide.nodes.Children$ProjectManagerDeadlockDetector.execute(Children.java:1921)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.postRequest(DefaultMutexImplementation.java:1022)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.postRequest(DefaultMutexImplementation.java:985)
   at org.netbeans.modules.openide.util.DefaultMutexImplementation.postWriteRequest(DefaultMutexImplementation.java:356)
   at org.openide.util.Mutex.postWriteRequest(Mutex.java:388)
   at org.openide.nodes.Children$Keys.applyKeys(Children.java:1565)
   at org.openide.nodes.Children$Keys.setKeys(Children.java:1509)
   at org.netbeans.modules.python.project.ui.PackageViewChildren.refreshKeys(PackageViewChildren.java:253)
   at org.netbeans.modules.python.project.ui.PackageViewChildren.access$000(PackageViewChildren.java:126)
   at org.netbeans.modules.python.project.ui.PackageViewChildren$1.run(PackageViewChildren.java:262)
   at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:312)
   at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:733)
   at java.awt.EventQueue.access$200(EventQueue.java:103)
   at java.awt.EventQueue$3.run(EventQueue.java:694)
   at java.awt.EventQueue$3.run(EventQueue.java:692)
   at java.security.AccessController.doPrivileged(AccessController.java:0)
   at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
   at java.awt.EventQueue.dispatchEvent(EventQueue.java:703)
   at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
   at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:242)
   at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:161)
   at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:150)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:146)
   at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:138)
   at java.awt.EventDispatchThread.run(EventDispatchThread.java:91)