The same project that is already opened upon MasterFileSystem is opened once
again, but on AbstractFileObjects comming from VCS filesystem. This happens as
soon as a file on Versioning tab is selected:

NEW J2SE Project on AbstractFileObject@1ac1adf[file:/home.local/martin/NETBEANS/TEST/CVS_WORK_LOCAL1/TestJavaCVSCommit/]
java.lang.Exception: Stack trace
        at java.lang.Thread.dumpStack(Thread.java:1158)
        at org.netbeans.modules.java.j2seproject.J2SEProject.<init>(J2SEProject.java:86)
        at org.netbeans.modules.java.j2seproject.J2SEProjectType.createProject(J2SEProjectType.java:41)
        at org.netbeans.modules.project.ant.AntBasedProjectFactorySingleton.loadProject(AntBasedProjectFactorySingleton.java:132)
        at org.netbeans.api.project.ProjectManager.createProject(ProjectManager.java:286)
        at org.netbeans.api.project.ProjectManager.access$700(ProjectManager.java:42)
        at org.netbeans.api.project.ProjectManager$2.run(ProjectManager.java:225)
        at org.openide.util.Mutex.readAccess(Mutex.java:220)
        at org.netbeans.api.project.ProjectManager.findProject(ProjectManager.java:175)
        at org.netbeans.modules.projectapi.SimpleFileOwnerQueryImplementation.getOwner(SimpleFileOwnerQueryImplementation.java:63)
        at org.netbeans.api.project.FileOwnerQuery.getOwner(FileOwnerQuery.java:68)
        at org.netbeans.modules.project.ui.actions.ActionsUtil.getProjectsFromLookup(ActionsUtil.java:85)
        at org.netbeans.modules.project.ui.actions.ProjectAction.refresh(ProjectAction.java:93)
        at org.netbeans.modules.project.ui.actions.LookupSensitiveAction.doRefresh(LookupSensitiveAction.java:106)
        at org.netbeans.modules.project.ui.actions.LookupSensitiveAction.resultChanged(LookupSensitiveAction.java:132)
        at sun.reflect.GeneratedMethodAccessor16.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
        at org.openide.util.WeakListenerImpl$ProxyListener.invoke(WeakListenerImpl.java:383)
        at $Proxy6.resultChanged(Unknown Source)
        at org.openide.util.lookup.AbstractLookup.notifyListeners(AbstractLookup.java:405)
        at org.openide.util.lookup.SimpleProxyLookup$ProxyResult.resultChanged(SimpleProxyLookup.java:226)
        at sun.reflect.GeneratedMethodAccessor16.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:585)
        at org.openide.util.WeakListenerImpl$ProxyListener.invoke(WeakListenerImpl.java:383)
        at $Proxy6.resultChanged(Unknown Source)
        at org.openide.util.lookup.AbstractLookup.notifyListeners(AbstractLookup.java:405)
        at org.openide.util.lookup.ProxyLookup$R.resultChanged(ProxyLookup.java:415)
        at org.openide.util.lookup.ProxyLookup.setLookups(ProxyLookup.java:109)
        at org.openide.windows.DefaultTopComponentLookup.updateLookups(DefaultTopComponentLookup.java:102)
        at org.openide.windows.TopComponent.setActivatedNodes(TopComponent.java:215)
        at org.openide.explorer.ExplorerPanel$PropL.propertyChange(ExplorerPanel.java:325)
        at org.openide.util.WeakListenerImpl$PropertyChange.propertyChange(WeakListenerImpl.java:131)
        at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:333)
        at java.beans.PropertyChangeSupport.firePropertyChange(PropertyChangeSupport.java:270)
        at org.openide.explorer.ExplorerManager$2.run(ExplorerManager.java:791)
        at org.openide.util.Mutex.doEvent(Mutex.java:1024)
        at org.openide.util.Mutex.readAccess(Mutex.java:239)
        at org.openide.explorer.ExplorerManager.fireInAWT(ExplorerManager.java:789)
        at org.openide.explorer.ExplorerManager.access$600(ExplorerManager.java:49)
        at org.openide.explorer.ExplorerManager$1AtomicSetSelectedNodes.updateSelection(ExplorerManager.java:208)
        at org.openide.explorer.ExplorerManager$1AtomicSetSelectedNodes.run(ExplorerManager.java:212)
        at org.openide.util.Mutex.readAccess(Mutex.java:246)
        at org.openide.explorer.ExplorerManager.setSelectedNodes(ExplorerManager.java:217)
        at org.netbeans.modules.vcscore.actions.VersioningExplorerAction$2.run(VersioningExplorerAction.java:174)
        at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:461)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:234)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:163)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:157)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:149)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:110)


There are then mixed files from MasterFS and VCS FS:

org.apache.tools.ant.module.api.support.ActionUtils.findSelectedFiles():
Matches (MasterFileObject@99210f[file:/home.local/martin/NETBEANS/TEST/CVS_WORK_LOCAL1/TestJavaCVSCommit/src/testFO/TestMasterFOs.java]) = true
  dir 'AbstractFileObject@c50561[file:/home.local/martin/NETBEANS/TEST/CVS_WORK_LOCAL1/TestJavaCVSCommit/src/]' is parent of 'MasterFileObject@99210f[file:/home.local/martin/NETBEANS/TEST/CVS_WORK_LOCAL1/TestJavaCVSCommit/src/testFO/TestMasterFOs.java]' = false

  FS1 = org.netbeans.modules.vcs.advanced.CommandLineVcsFileSystem /home.local/martin/NETBEANS/TEST/CVS_WORK_LOCAL1[org.netbeans.modules.vcs.advanced.CommandLineVcsFileSystem@a2ba05],
  FS2 = org.netbeans.modules.masterfs.MasterFileSystem[org.netbeans.modules.masterfs.MasterFileSystem@d88aa2]