DescribeInternetGateways fails to parse attachmentSet state

[theunixman]

[Client Request] {
  host      = ec2.us-east-1.amazonaws.com:443
  secure    = True
  method    = POST
  target    = Nothing
  timeout   = Just 70000000
  redirects = 0
  path      = /
  query     =
  headers   = host: ec2.us-east-1.amazonaws.com; x-amz-date: 20160319T211028Z; x-amz-content-sha256: 4354fa01be0d9c7f8b11b87f837f5abb46dc4d940438238843d35ed53b472fe8; content-type: application/x-www-form-urlencoded; charset=utf-8; authorization: AWS4-HMAC-SHA256 Credential=AKIAJZCUFNACIHRMP4TQ/20160319/us-east-1/ec2/aws4_request, SignedHeaders=content-type;host;x-amz-content-sha256;x-amz-date, Signature=08db9f21a25e173f12e2d66c1ec48e40d9a4233cb92f831f175c3d8bf92abda0
  body      = Action=DescribeInternetGateways&Filter.1.Name=attachment.vpc-id&Filter.1.Value.1=vpc-eff8c28b&Version=2015-10-01
}
[Client Response] {
  status  = 200 OK
  headers = content-type: text/xml;charset=UTF-8; transfer-encoding: chunked; content-encoding: gzip; vary: Accept-Encoding; date: Sat, 19 Mar 2016 21:10:27 GMT; server: AmazonEC2
}
[Raw Response Body] {
<?xml version="1.0" encoding="UTF-8"?>
<DescribeInternetGatewaysResponse xmlns="http://ec2.amazonaws.com/doc/2015-10-01/">
    <requestId>486604d2-f155-4c81-8cde-89df19665b62</requestId>
    <internetGatewaySet>
        <item>
            <internetGatewayId>igw-2447fb40</internetGatewayId>
            <attachmentSet>
                <item>
                    <vpcId>vpc-eff8c28b</vpcId>
                    <state>available</state>
                </item>
            </attachmentSet>
            <tagSet>
                <item>
                    <key>Name</key>
                    <value>IGW</value>
                </item>
            </tagSet>
        </item>
    </internetGatewaySet>
</DescribeInternetGatewaysResponse>
}
[SerializeError] {
  service = EC2
  status  = 200 OK
  message = Failed reading: Failure parsing AttachmentStatus from value: 'available'. Accepted values: attached, attaching, busy, detached, detaching
}
vpc: SerializeError (SerializeError' {_serializeAbbrev = Abbrev "EC2", _serializeStatus = Status {statusCode = 200, statusMessage = "OK"}, _serializeMessage = "Failed reading: Failure parsing AttachmentStatus from value: 'available'. Accepted values: attached, attaching, busy, detached, detaching"})