Test failures in py26 environment

Current Keystone trunk, I see test failures when I run "tox -e py26", apparently related to an inability to call an external program and/or to verify a token. Examples include:

  ======================================================================
  ERROR: test_fetch_revocation_list (test_auth_token_middleware.AuthTokenMiddlewareTest)
  ----------------------------------------------------------------------
  Traceback (most recent call last):
    File "/home/klmitch/devel/src/keystone/tests/test_auth_token_middleware.py", line 490, in test_fetch_revocation_list
      fetched_list = jsonutils.loads(self.middleware.fetch_revocation_list())
    File "/home/klmitch/devel/src/keystone/keystone/middleware/auth_token.py", line 782, in fetch_revocation_list
      return self.cms_verify(data['signed'])
    File "/home/klmitch/devel/src/keystone/keystone/middleware/auth_token.py", line 711, in cms_verify
      self.ca_file_name)
    File "/home/klmitch/devel/src/keystone/keystone/common/cms.py", line 23, in cms_verify
      output, err = process.communicate(formatted)
    File "/usr/lib/python2.6/subprocess.py", line 691, in communicate
      return self._communicate(input)
    File "/usr/lib/python2.6/subprocess.py", line 1222, in _communicate
      bytes_written = os.write(self.stdin.fileno(), chunk)
  OSError: [Errno 32] Broken pipe
  -------------------- >> begin captured logging << --------------------
  keystone.middleware.auth_token: INFO: Starting keystone auth_token middleware
  keystone.middleware.auth_token: INFO: Using signing as cache directory for signing certificate
  --------------------- >> end captured logging << ---------------------

  ======================================================================
  ERROR: test_get_revocation_list_returns_fetched_list (test_auth_token_middleware.AuthTokenMiddlewareTest)
  ----------------------------------------------------------------------
  Traceback (most recent call last):
    File "/home/klmitch/devel/src/keystone/tests/test_auth_token_middleware.py", line 472, in test_get_revocation_list_returns_fetched_list
      self.assertEqual(self.middleware.token_revocation_list,
    File "/home/klmitch/devel/src/keystone/keystone/middleware/auth_token.py", line 759, in token_revocation_list
      self.token_revocation_list = self.fetch_revocation_list()
    File "/home/klmitch/devel/src/keystone/keystone/middleware/auth_token.py", line 769, in token_revocation_list
      self._token_revocation_list = jsonutils.loads(value)
    File "/home/klmitch/devel/src/keystone/keystone/openstack/common/jsonutils.py", line 132, in loads
      return json.loads(s)
    File "/usr/lib/python2.6/json/__init__.py", line 307, in loads
      return _default_decoder.decode(s)
    File "/usr/lib/python2.6/json/decoder.py", line 319, in decode
      obj, end = self.raw_decode(s, idx=_w(s, 0).end())
    File "/usr/lib/python2.6/json/decoder.py", line 338, in raw_decode
      raise ValueError("No JSON object could be decoded")
  ValueError: No JSON object could be decoded
  -------------------- >> begin captured logging << --------------------
  keystone.middleware.auth_token: INFO: Starting keystone auth_token middleware
  keystone.middleware.auth_token: INFO: Using signing as cache directory for signing certificate
  --------------------- >> end captured logging << ---------------------

Full test run log attached.