Why is JBoss EAP 6.4.0 throwing a NullPointerException when using Kerberos authentication over SSL for remote EJBs?

Issue

Why is JBoss EAP 6.4.0 throwing a NullPointerException when using Kerberos authentication over SSL for remote EJBs?

11:55:08,803 TRACE [org.jboss.modules] (Remoting "localhost" task-1) Found previously loaded class org.jboss.remoting3.remote.ServerConnectionOpenListener$AuthStepRunnable from Module "org.jboss.remoting3:main" from local module loader @423798e2 (finder: local module finder @50163f64 (roots: /home/dehort/dev/java/jboss-eap-6.4.0/modules,/home/dehort/dev/java/jboss-eap-6.4.0/modules/system/layers/base))
11:55:08,801 TRACE [org.jboss.remoting.remote.server] (Remoting "localhost" task-1) Server sending authentication rejected: java.lang.NullPointerException
    at com.sun.security.sasl.util.AbstractSaslImpl.traceOutput(AbstractSaslImpl.java:259) [rt.jar:1.7.0_45]
    at com.sun.security.sasl.gsskerb.GssKrb5Server.evaluateResponse(GssKrb5Server.java:159) [rt.jar:1.7.0_45]
    at org.jboss.sasl.gssapi.GssapiServer$1.run(GssapiServer.java:60) [jboss-sasl-1.0.5.Final-redhat-1.jar:1.0.5.Final-redhat-1]
    at org.jboss.sasl.gssapi.GssapiServer$1.run(GssapiServer.java:56) [jboss-sasl-1.0.5.Final-redhat-1.jar:1.0.5.Final-redhat-1]
    at java.security.AccessController.doPrivileged(Native Method) [rt.jar:1.7.0_45]
    at javax.security.auth.Subject.doAs(Subject.java:415) [rt.jar:1.7.0_45]
    at org.jboss.sasl.gssapi.GssapiServer.evaluateResponse(GssapiServer.java:56) [jboss-sasl-1.0.5.Final-redhat-1.jar:1.0.5.Final-redhat-1]
    at org.xnio.sasl.SaslUtils.evaluateResponse(SaslUtils.java:194) [xnio-api-3.0.13.GA-redhat-1.jar:3.0.13.GA-redhat-1]
    at org.jboss.remoting3.remote.ServerConnectionOpenListener$AuthStepRunnable.run(ServerConnectionOpenListener.java:491) [jboss-remoting-3.3.4.Final-redhat-1.jar:3.3.4.Final-redhat-1]
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_45]
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_45]
    at java.lang.Thread.run(Thread.java:744) [rt.jar:1.7.0_45]