Fix https://issues.apache.org/bugzilla/show_bug.cgi?id=56529
Followup to r1595230
Minor improvement to the testcase: check the actual response produced by test JSP page.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/trunk@1595365 13f79535-47bb-0310-9956-ffa450edef68