By default, deploying a WAR or EAR without a geronimo-tomcat.xml results in the use of a default deployment plan.
The web.xml webapp id, or the base archive file name is used as a configuration id, and also for the root context. This is consistent with Jetty and OpenEJB behavior, and an ease-of-use feature by design.
A minor bug during the creation of the default plan, in TomcatModuleBuilder.java, prevents the root context from being created properly. The attached patch should fix this.