org.jboss.test.security.test.NegotiationTestCase.testIdentityPropagation intermittently fails on EAP 5.3.0 due to 'Unexpected status code returned after the authentication. expected:<200> but was:<500>'

Stacktrace

junit.framework.AssertionFailedError: Unexpected status code returned after the authentication. expected:<200> but was:<500>
at org.jboss.test.security.negotiation.NegotiationUtils$2.run(NegotiationUtils.java:185)
at org.jboss.test.security.negotiation.NegotiationUtils$2.run(NegotiationUtils.java:180)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.jboss.test.security.negotiation.NegotiationUtils.makeHttpCall(NegotiationUtils.java:179)
at org.jboss.test.security.test.NegotiationTestCase.testIdentityPropagation(NegotiationTestCase.java:93)

In negotiation server log there is
2014-02-10 18:29:08,060 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/spnego-web-test].[PropagateIdentityServlet]] (http-10.16.95.126-8080-1) Servlet.service() for servlet PropagateIdentityServlet threw exception
java.net.ConnectException: Connection refused
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:351)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:213)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:200)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:529)
at org.jboss.test.security.negotiation.GSSTestClient.getName(GSSTestClient.java:98)
at org.jboss.test.security.negotiation.PropagateIdentityServlet.doGet(PropagateIdentityServlet.java:77)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.jboss.security.negotiation.NegotiationAuthenticator$1.invoke(NegotiationAuthenticator.java:326)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:534)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:95)
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.internalProcess(ActiveRequestResponseCacheValve.java:74)
at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.invoke(ActiveRequestResponseCacheValve.java:47)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:599)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:452)
at java.lang.Thread.run(Thread.java:662)

See: https://jenkins.mw.lab.eng.bos.redhat.com/hudson/view/EAP5/view/AS-TestSuite/job/eap-5.3.x-JDK6-RHEL6-matrix-CI/jdk=java16_default,label_exp=RHEL6%26%26x86_64/78/testReport/junit/org.jboss.test.security.test/NegotiationTestCase/testIdentityPropagation/