Invocations on UserTransaction obtained from InitialContext don't take user credentials into account

Properties props = new Properties();
props.put(Context.INITIAL_CONTEXT_FACTORY, WildFlyInitialContextFactory.class.getName());
props.put(Context.PROVIDER_URL, "remote+http://127.0.0.1:8080");
props.put(Context.SECURITY_PRINCIPAL, "joe");
props.put(Context.SECURITY_CREDENTIALS, "joeIsAwesome2013!");
InitialContext ctx = new InitialContext(props);
UserTransaction tx = (UserTransaction)ctx.lookup("txn:UserTransaction");
tx.begin();

Exception in thread "main" javax.transaction.SystemException: WFTXN0021: Failed to acquire a connection for this operation
	at org.wildfly.transaction.client.provider.remoting.RemotingRemoteTransactionPeer.begin(RemotingRemoteTransactionPeer.java:168)
	at org.wildfly.transaction.client.RemoteUserTransaction.begin(RemoteUserTransaction.java:62)
	at client.Client.main(Client.java:26)
Caused by: javax.security.sasl.SaslException: Authentication failed: none of the mechanisms presented by the server (JBOSS-LOCAL-USER, DIGEST-MD5) are supported
	at org.jboss.remoting3.remote.ClientConnectionOpenListener$Capabilities.handleEvent(ClientConnectionOpenListener.java:426)
	at org.jboss.remoting3.remote.ClientConnectionOpenListener$Capabilities.handleEvent(ClientConnectionOpenListener.java:241)
	at org.xnio.ChannelListeners.invokeChannelListener(ChannelListeners.java:92)
	at org.xnio.conduits.ReadReadyHandler$ChannelListenerHandler.readReady(ReadReadyHandler.java:66)
	at org.xnio.nio.NioSocketConduit.handleReady(NioSocketConduit.java:89)
	at org.xnio.nio.WorkerThread.run(WorkerThread.java:567)
	at ...asynchronous invocation...(Unknown Source)
	at org.jboss.remoting3.EndpointImpl.connect(EndpointImpl.java:465)
	at org.jboss.remoting3.FutureConnection.getConnection(FutureConnection.java:117)
	at org.jboss.remoting3.FutureConnection.init(FutureConnection.java:77)
	at org.jboss.remoting3.FutureConnection.get(FutureConnection.java:152)
	at org.jboss.remoting3.EndpointImpl.doGetConnection(EndpointImpl.java:407)
	at org.jboss.remoting3.EndpointImpl.getConnection(EndpointImpl.java:341)
	at org.jboss.remoting3.UncloseableEndpoint.getConnection(UncloseableEndpoint.java:55)
	at org.jboss.remoting3.Endpoint.getConnection(Endpoint.java:135)
	at org.wildfly.transaction.client.provider.remoting.RemotingRemoteTransactionPeer.lambda$getOperations$0(RemotingRemoteTransactionPeer.java:63)
	at java.security.AccessController.doPrivileged(Native Method)
	at org.wildfly.transaction.client.provider.remoting.RemotingRemoteTransactionPeer.getOperations(RemotingRemoteTransactionPeer.java:63)
	at org.wildfly.transaction.client.provider.remoting.RemotingRemoteTransactionPeer.begin(RemotingRemoteTransactionPeer.java:166)
	... 2 more