Log4J Appenders configured in logging subsystem don't work in EAP 6.1.0

Issue

• I configured a Log4J appender as a <custom-handler> in my logging subystem. It works fine the first time I start JBoss, but every time afterwards it fails:

2013-05-06 11:19:44,724 WARN  [org.jboss.as.logging] (Controller Boot Thread) JBAS011511: Replacing handler 'SYSLOG' during add operation. Either the handler type or the module name differs from the initial configuration.
 java.lang.NullPointerException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.jboss.logmanager.config.AbstractPropertyConfiguration$1.applyPostCreate(AbstractPropertyConfiguration.java:218)
    at org.jboss.logmanager.config.AbstractPropertyConfiguration$1.applyPostCreate(AbstractPropertyConfiguration.java:198)
    at org.jboss.logmanager.config.LogContextConfigurationImpl.doApplyPostCreate(LogContextConfigurationImpl.java:316)
    at org.jboss.logmanager.config.LogContextConfigurationImpl.doPrepare(LogContextConfigurationImpl.java:341)
    at org.jboss.logmanager.config.LogContextConfigurationImpl.prepare(LogContextConfigurationImpl.java:290)

• Another form of this issue looks like this log snippet:

22:13:19,825 INFO  [org.jboss.remoting] (MSC service thread 1-8) JBoss Remoting version 3.2.16.GA-redhat-1
22:13:20,958 WARN  [org.jboss.as.logging] (Controller Boot Thread) JBAS011511: Replacing handler 'APPLMON' during add operation. Either the handler type or the module name differs from the initial configuration.
22:13:20,998 ERROR [stderr] (pool-1-thread-1) java.util.logging.ErrorManager: 1: Publication error
22:13:20,998 ERROR [stderr] (pool-1-thread-1) java.lang.IllegalStateException: JBAS011560: The handler is closed, cannot publish to a closed handler
22:13:21,000 ERROR [stderr] (pool-1-thread-1) at org.jboss.as.logging.logmanager.Log4jAppenderHandler.doPublish(Log4jAppenderHandler.java:126)
22:13:21,000 ERROR [stderr] (pool-1-thread-1) at org.jboss.logmanager.ExtHandler.publish(ExtHandler.java:76)
22:13:21,001 ERROR [stderr] (pool-1-thread-1) at org.jboss.logmanager.handlers.AsyncHandler$AsyncTask.run(AsyncHandler.java:199)
22:13:21,002 ERROR [stderr] (pool-1-thread-1) at java.lang.Thread.run(Thread.java:662)