Requests Stacktrace

test_css (tests.test_css.CSSTest) ... Servlet has thrown exception:java.lang.IllegalStateException: Reader used
ERROR

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ERROR: test_css (tests.test_css.CSSTest)
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Traceback (most recent call last):
  File "/home/pritishc/RestOfFileSystem/nereid-stuff/nereid-webshop/tests/test_css.py", line 49, in test_css
    result = self.validate(cssfile)
  File "/home/pritishc/RestOfFileSystem/nereid-stuff/nereid-webshop/tests/test_css.py", line 40, in validate
    result = json.loads(response)
  File "/usr/lib/python2.7/json/__init__.py", line 338, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 366, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
TypeError: expected string or buffer