The existing assumption from Issue #12 about server.getHandlers() is also true for undeploy(Archive). Also, the removeHandler logic assumption is incorrect. See [StandardUndeployer.java](https://github.com/eclipse/jetty.project/blob/jetty-9.1/jetty-deploy/src/main/java/org/eclipse/jetty/deploy/bindings/StandardUndeployer.java) for details.