Comment 5 for bug 945176

This is the output of the test program. Note that the backtrace about NoneType is normal (coding error due to my ignorance of how to do things perfectly in twisted).

$ python test-txaws-ipaddress.py ami-9666e9a6
i-e5269ad6
Mon Aug 6 16:32:33 2012: polling ec2...
Mon Aug 6 16:32:33 2012: polling ec2...
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/twisted/protocols/policies.py", line 123, in connectionLost
    self.wrappedProtocol.connectionLost(reason)
  File "/usr/lib/python2.7/dist-packages/twisted/web/client.py", line 191, in connectionLost
    self.factory._disconnectedDeferred.callback(None)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 362, in callback
    self._startRunCallbacks(result)
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 458, in _startRunCallbacks
    self._runCallbacks()
--- <exception caught here> ---
  File "/usr/lib/python2.7/dist-packages/twisted/internet/defer.py", line 545, in _runCallbacks
    current.result = callback(current.result, *args, **kw)
  File "test-txaws-ipaddress.py", line 69, in describeInstances
    d = ec2.describe_instances(instance_id)
  File "/usr/lib/python2.7/dist-packages/txaws/ec2/client.py", line 45, in describe_instances
    d = query.submit()
  File "/usr/lib/python2.7/dist-packages/txaws/ec2/client.py", line 976, in submit
    self.sign()
  File "/usr/lib/python2.7/dist-packages/txaws/ec2/client.py", line 969, in sign
    self.params["Signature"] = self.signature.compute()
  File "/usr/lib/python2.7/dist-packages/txaws/ec2/client.py", line 1022, in compute
    bytes = self.signing_text()
  File "/usr/lib/python2.7/dist-packages/txaws/ec2/client.py", line 1041, in signing_text
    self.get_canonical_query_params())
  File "/usr/lib/python2.7/dist-packages/txaws/ec2/client.py", line 1048, in get_canonical_query_params
    result.append("%s=%s" % (self.encode(key), self.encode(value)))
  File "/usr/lib/python2.7/dist-packages/txaws/ec2/client.py", line 1059, in encode
    return quote(string, safe="~")
  File "/usr/lib/python2.7/urllib.py", line 1255, in quote
    raise TypeError('None object cannot be quoted')
exceptions.TypeError: None object cannot be quoted
Mon Aug 6 16:32:43 2012: polling ec2...
Mon Aug 6 16:32:53 2012: polling ec2...
Mon Aug 6 16:33:04 2012: polling ec2...
Mon Aug 6 16:33:15 2012: polling ec2...
dns_name = ec2-54-245-9-232.us-west-2.compute.amazonaws.com
ip_address = 54.245.9.232
private_dns_name = ip-10-248-27-120.us-west-2.compute.internal
private_ip_address = 10.248.27.120
[('i-e5269ad6', 'running', 'shutting-down')]

When run on precise w/o this backport, ip_address will = None