title: A leading 0 bug in dataframe?
body: <p>It seems that a leading 0 in a number causes error in dataframes. Can anybody replicate?</p>
  
  <pre><code>In [45]: df = pd.DataFrame({'hhmm': [930,1000,1300]})
  In [46]: df = pd.DataFrame({'hhmm': [0930,1000,1300]})
    File "&lt;ipython-input-46-3a3038c84b16&gt;", line 1
      df = pd.DataFrame({'hhmm': [0930,1000,1300]})
                                     ^
  SyntaxError: invalid token
  In [47]: 
  </code></pre>