It was first noticed when running the tests in the test/functional directory on the RHEL 5 hudson slave. The traceback from those tests is:

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ERROR: test_oauth_header (test_oauth.TestOauth)
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Traceback (most recent call last):
  File "/home/jenkins/workspace/pulp-dev-rhel5/test/functional/test_oauth.py", line 62, in test_oauth_header
    oauth_request.sign_request(oauth.SignatureMethod_HMAC_SHA1(), consumer, None)
  File "/usr/lib/python2.4/site-packages/oauth2/__init__.py", line 502, in sign_request
    self['oauth_signature'] = signature_method.sign(self, consumer, token)
  File "/usr/lib/python2.4/site-packages/oauth2/__init__.py", line 843, in sign
    hashed = hmac.new(key, raw, sha)
  File "/usr/lib64/python2.4/hmac.py", line 107, in new
    return HMAC(key, msg, digestmod)
  File "/usr/lib64/python2.4/hmac.py", line 42, in __init__
    self.outer = digestmod.new()
AttributeError: 'builtin_function_or_method' object has no attribute 'new'