title: assertRises failure
body: <p>I'm trying to write a unit test that will ensure an HTTPException is raised when necessary. Here is the test:</p>
  
  <pre><code>import unittest  
  from requests import HTTPError
  import pyport
  
   # Code omitted...
   def test_bad_item_type(self):
       """A bad item type should raise a HTTPError"""
       test_type = 'bad'
       test_id = 1986134
       self.assertRaises(HTTPError, pyport.get_item(test_type, test_id))
  </code></pre>
  
  <p>Which produces the following:</p>
  
  <pre><code>ERROR: test_bad_item_type (__main__.TestPyportFunctions) A bad item
  type should raise requests.HTTPError
  ---------------------------------------------------------------------- 
  Traceback (most   recent call last):   File "./tests.py", line 65, in
  test_bad_item_type
      self.assertRaises(HTTPError, pyport.get_item(test_type, test_id))   File    "/home/sean/workspace/pyport/pyport.py", line 54, in get_item
      response.raise_for_status()   File "/usr/local/lib/python2.7/dist-packages/requests/models.py", line 741, fin raise_for_status
      raise HTTPError('%s Client Error' % self.status_code) HTTPError: 404 Client Error
  </code></pre>
  
  <p>The exception is raised, but it is not caught by the test. This is similar to what happened in <a href="https://stackoverflow.com/questions/6972703/assertraises-fails-even-though-exception-is-raised">this question</a>, but it is not quite the same. Can someone tell me what I'm missing? </p>