Comment 2 for bug 1656891

Traceback looks something like

Mar 7 18:52:17 saio proxy-server: Error: An error occurred:
Traceback (most recent call last):
  File "/vagrant/swift/swift/common/middleware/catch_errors.py", line 41, in handle_request
    resp = self._app_call(env)
  File "/vagrant/swift/swift/common/wsgi.py", line 1058, in _app_call
    resp = self.app(env, self._start_response)
  File "/vagrant/swift/swift/common/middleware/gatekeeper.py", line 102, in __call__
    return self.app(env, gatekeeper_response)
  File "/vagrant/swift/swift/common/middleware/healthcheck.py", line 52, in __call__
    return self.app(env, start_response)
  File "/vagrant/swift/swift/common/middleware/proxy_logging.py", line 346, in __call__
    six.reraise(exc_type, exc_value, exc_traceback)
  File "/vagrant/swift/swift/common/middleware/proxy_logging.py", line 338, in __call__
    iterable = self.app(env, my_start_response)
  File "/vagrant/swift/swift/common/middleware/copy.py", line 318, in __call__
    return self.app(env, start_response)
  File "/vagrant/swift/swift/common/middleware/cname_lookup.py", line 135, in __call__
    ttl, found_domain = lookup_cname(a_domain)
  File "/vagrant/swift/swift/common/middleware/cname_lookup.py", line 58, in lookup_cname
    answer = dns.resolver.query(domain, 'CNAME').rrset
  File "/usr/local/lib/python2.7/dist-packages/eventlet/support/dns/resolver.py", line 1132, in query
    raise_on_no_answer, source_port)
  File "/usr/local/lib/python2.7/dist-packages/eventlet/support/dns/resolver.py", line 1051, in query
    raise NXDOMAIN(qnames=qnames_to_try, responses=nxdomain_responses)
NXDOMAIN: The DNS query name does not exist: saio.swiftstack.org. (txn: tx96c22536d08d443d94b81-0058bf0161)