Problem Accessing Grails Layouts

Just a quick note for posterity: If you're running a grails app (or probably any webapp) on jetty, and you configure the app to use the root (/) contextPath, and you leave jetty's default root webapp (/usr/share/jetty/webapps/root) around, you're in for a world of hurt. With grails, you'll get an obtuse 404 error page with the following message:

Problem accessing /WEB-INF/grails-app/views/layouts/my-custom-layout.gsp

(And no info in the logs.) The fix is of course to delete that vestigial root webapp.