Mode test for adding duplicates from setUp() into a test method.
Add two additional tests.
It is backport of r1604217.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1604845 13f79535-47bb-0310-9956-ffa450edef68
Test for https://issues.apache.org/bugzilla/show_bug.cgi?id=56653
Test concurrency issue with Mapper$ContextList.nesting field.
It is backport of r1604309.

git-svn-id: https://svn.apache.org/repos/asf/tomcat/tc7.0.x/trunk@1604846 13f79535-47bb-0310-9956-ffa450edef68