The org.jboss.test.ws.jaxws.cxf.noIntegration.CXFEndpointServlet that is used by the DisabledWSSubsystemTestCase is leaving the bus created within the CXFNonSpringServlet assigned to the thread that's serving the servlet init() method.
That can lead to intermittent failures in other tests that use the Endpoint.publish(..) api for starting endpoints within other servlets.