Program: 118945
Project: 118945
Buggy source:
private void fillUIBranches(final Project project,boolean lastUsedBranch){
  if (LoginHelper.isRemoteConnection(getConnection())) {
    currentProjectSettings=project;
    final List<String> projectBranches=new ArrayList<String>();
    projectBranches.add("String_Node_Str");
    branchesViewer.setInput(projectBranches);
    branchesViewer.setSelection(new StructuredSelection(new Object[]{"String_Node_Str"}));
    branchesViewer.getCombo().setEnabled(false);
    if (backgroundGUIUpdate == null) {
      backgroundGUIUpdate=new Job("String_Node_Str"){
        @Override protected IStatus run(        IProgressMonitor monitor){
          projectBranches.clear();
          projectBranches.addAll(loginHelper.getProjectBranches(currentProjectSettings));
          return org.eclipse.core.runtime.Status.OK_STATUS;
        }
      }
;
      Job.getJobManager().addJobChangeListener(new JobChangeAdapter(){
        @Override public void done(        IJobChangeEvent event){
          if (event.getJob().equals(backgroundGUIUpdate)) {
            if (branchesViewer != null && !branchesViewer.getCombo().isDisposed()) {
              branchesViewer.getCombo().getDisplay().syncExec(new Runnable(){
                @Override public void run(){
                  branchesViewer.setInput(projectBranches);
                  branchesViewer.setSelection(new StructuredSelection(new Object[]{"String_Node_Str"}));
                  branchesViewer.getCombo().setEnabled(projectViewer.getControl().isEnabled());
                }
              }
);
            }
          }
        }
      }
);
      branchesViewer.getCombo().addDisposeListener(new DisposeListener(){
        @Override public void widgetDisposed(        DisposeEvent e){
          backgroundGUIUpdate=null;
        }
      }
);
    }
    backgroundGUIUpdate.schedule();
  }
}

Fixed version (ground truth):
private void fillUIBranches(final Project project,boolean lastUsedBranch){
  if (LoginHelper.isRemoteConnection(getConnection())) {
    currentProjectSettings=project;
    final List<String> projectBranches=new ArrayList<String>();
    projectBranches.add("String_Node_Str");
    branchesViewer.setInput(projectBranches);
    branchesViewer.setSelection(new StructuredSelection(new Object[]{"String_Node_Str"}));
    branchesViewer.getCombo().setEnabled(false);
    if (backgroundGUIUpdate == null) {
      backgroundGUIUpdate=new Job("String_Node_Str"){
        @Override protected IStatus run(        IProgressMonitor monitor){
          projectBranches.clear();
          projectBranches.addAll(loginHelper.getProjectBranches(currentProjectSettings));
          return org.eclipse.core.runtime.Status.OK_STATUS;
        }
      }
;
      Job.getJobManager().addJobChangeListener(new JobChangeAdapter(){
        @Override public void done(        IJobChangeEvent event){
          if (event.getJob().equals(backgroundGUIUpdate)) {
            if (branchesViewer != null && !branchesViewer.getCombo().isDisposed()) {
              branchesViewer.getCombo().getDisplay().syncExec(new Runnable(){
                @Override public void run(){
                  if (branchesViewer == null || branchesViewer.getControl() == null || branchesViewer.getControl().isDisposed()) {
                    return;
                  }
                  branchesViewer.setInput(projectBranches);
                  branchesViewer.setSelection(new StructuredSelection(new Object[]{"String_Node_Str"}));
                  branchesViewer.getCombo().setEnabled(projectViewer.getControl().isEnabled());
                }
              }
);
            }
          }
        }
      }
);
      branchesViewer.getCombo().addDisposeListener(new DisposeListener(){
        @Override public void widgetDisposed(        DisposeEvent e){
          backgroundGUIUpdate=null;
        }
      }
);
    }
    backgroundGUIUpdate.schedule();
  }
}