https://issues.apache.org/bugzilla/show_bug.cgi?id=56657
If sessionid belongs to the latest version of webapp, use the latest version.
Merged r1604605 from tomcat/trunk.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1604607 13f79535-47bb-0310-9956-ffa450edef68