title: Pandas concat failing
body: <p>I am trying to concat dataframes based on the foll. 2 csv files:</p>
  
  <p>df_a: <a href="https://www.dropbox.com/s/slcu7o7yyottujl/df_current.csv?dl=0" rel="noreferrer">https://www.dropbox.com/s/slcu7o7yyottujl/df_current.csv?dl=0</a></p>
  
  <p>df_b: <a href="https://www.dropbox.com/s/laveuldraurdpu1/df_climatology.csv?dl=0" rel="noreferrer">https://www.dropbox.com/s/laveuldraurdpu1/df_climatology.csv?dl=0</a></p>
  
  <p>Both of these have the same number and names of columns. However, when I do this:</p>
  
  <pre><code>pandas.concat([df_a, df_b])
  </code></pre>
  
  <p>I get the error:</p>
  
  <pre><code>AssertionError: Number of manager items must equal union of block items
  # manager items: 20, # tot_items: 21
  </code></pre>
  
  <p>How to fix this?</p>