title: xlrd throws TypeError: embedded NUL character when trying to open an `.xls` file from web in Python 3.4
body: <p>I am trying to open an excel file from the web and extract one of the columns.  However, when I try to open the file with <code>xlrd</code> I get an error.  The code I am trying is:</p>
  
  <pre><code>from urllib.request import urlopen
  import xlrd
  DJIA_URL = 'http://www.djaverages.com/?go=export-components&amp;symbol=DJI'
  xlfile = urlopen(DJIA_URL).read()
  xlbook = xlrd.open_workbook(xlfile)
  </code></pre>
  
  <p>however, I am getting a type error:</p>
  
  <pre><code>Traceback (most recent call last):
    File "C:\Code\development\Pynance\pynance\sources\indices.py", line 31, in &lt;module&gt;
      xlbook = xlrd.open_workbook(xlfile)
    File "C:\Python34\lib\site-packages\xlrd\__init__.py", line 394, in open_workbook
      f = open(filename, "rb")
  TypeError: embedded NUL character
  [Finished in 0.8s with exit code 1]
  </code></pre>
  
  <p>If I download the file manually and open it like:</p>
  
  <pre><code>xlfile = 'DJIComponents.xls'
  xlbook = xlrd.open_workbook(xlfile)
  </code></pre>
  
  <p>no problems, I would just rather skip the manual step.  Is there an encoding setting or something I am missing?</p>