title: Issue reading pickle file created from higher version but need to use in lower version
body: <p>I created pickle file using version pandas  0.22.2 py 3.6 but when im trying to use in pandas 0.18.1 version ca't able to load follwing error ,
  mportError: No module named 'pandas.core.indexes'</p>
  
  <p>even i tried using pd.read_pickle</p>
  
  <p>please help on this issue</p>