title: read_csv doesn't read the column names correctly on this file?
body: <p>I have a csv file as follows:</p>
  
  <pre><code>0 5
  1 10
  2 15
  3 20
  4 25
  </code></pre>
  
  <p>I want to save it as a dataframe with x,y axes as names, then plot it. However when I assign <code>x</code>,<code>y</code> I get a messed up DataFrame, what is happening?</p>
  
  <pre><code>column_names = ['x','y']
  x = pd.read_csv('csv-file.csv', header = None, names = column_names)
  print(x)
  
            x   y
  0   0 5 NaN
  1  1 10 NaN
  2  2 15 NaN
  3  3 20 NaN
  4  4 25 NaN
  </code></pre>
  
  <p>I've tried without specifying <code>None</code> for <code>header</code>, to no avail.</p>