HTTPCLIENT-1535: Permit other addresses to be tried in the event of a NoRouteToHostException. e.g. when there one of the addresses to be used is an ipv6 address when the client does not have an ipv6 route to that particular host
httpcomponents/httpclient/trunk/httpclient/src/main/java/org/apache/http/impl/conn/DefaultHttpClientConnectionOperator.java