HTTPCLIENT-1542: Caching HttpClient uses absolute URIs for validation
Based on contribution by Joseph Walton <joe at kafsemo.org>

git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/branches/4.3.x@1618323 13f79535-47bb-0310-9956-ffa450edef68