run Jetty from outside the target so that you have to use -PcleanJetty to clean up, generally persisting the server and configuration that you used across clean builds
archiva/branches/MRM-1025/archiva-modules/archiva-web/archiva-webapp/
archiva/branches/MRM-1025/archiva-modules/archiva-web/archiva-webapp/src/appserver-base/conf/archiva.xml