I'm seeing this error quite a lot when running the tests:

16:20:27,660 WARN [AspectDeployer] Error undeploying xml jboss-aop.xml
java.util.ConcurrentModificationException
 at java.util.WeakHashMap$HashIterator.nextEntry(WeakHashMap.java:744)
 at java.util.WeakHashMap$KeyIterator.next(WeakHashMap.java:777)
 at org.jboss.aop.advice.AspectDefinition.undeploy(AspectDefinition.java:73)
 at org.jboss.aop.AspectManager.internalRemoveAspectDefintion(AspectManager.java:1830)
 at org.jboss.aop.deployment.ScopedClassLoaderDomain.removeAspectDefinition(ScopedClassLoaderDomain.java:73)
 at org.jboss.aop.AspectXmlLoader.bulkUndeploy(AspectXmlLoader.java:1134)
 at org.jboss.aop.AspectXmlLoader.undeployXML(AspectXmlLoader.java:1116)
 at org.jboss.aop.deployers.temp.AspectDeployer.undeployXml(AspectDeployer.java:208)
 at org.jboss.aop.deployers.temp.AspectDeployer.undeployXml(AspectDeployer.java:188)
 at org.jboss.aop.deployers.temp.AspectDeployer.undeploy(AspectDeployer.java:127)
 at org.jboss.deployers.vfs.spi.deployer.AbstractVFSRealDeployer.undeploy(AbstractVFSRealDeployer.java:54)
 at org.jboss.deployers.plugins.deployers.DeployerWrapper.undeploy(DeployerWrapper.java:182)
 at org.jboss.deployers.plugins.deployers.DeployersImpl.doUninstall(DeployersImpl.java:753)
 at org.jboss.deployers.plugins.deployers.DeployersImpl.doUninstall(DeployersImpl.java:724)
 at org.jboss.deployers.plugins.deployers.DeployersImpl.uninstall(DeployersImpl.java:702)
 at org.jboss.dependency.plugins.AbstractControllerContext.uninstall(AbstractControllerContext.java:311)
 at org.jboss.dependency.plugins.AbstractController.uninstall(AbstractController.java:1271)
 at org.jboss.dependency.plugins.AbstractController.uninstallContext(AbstractController.java:960)
 at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:578)
 at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:374)
 at org.jboss.deployers.plugins.deployers.DeployersImpl.process(DeployersImpl.java:361)
 at org.jboss.deployers.plugins.main.MainDeployerImpl.process(MainDeployerImpl.java:340)
 at org.jboss.deployment.MainDeployer.undeploy(MainDeployer.java:638)
 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:585)
 at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:157)
 at org.jboss.mx.server.Invocation.dispatch(Invocation.java:96)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
 at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:668)
 at sun.reflect.GeneratedMethodAccessor100.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.jmx.connector.invoker.InvokerAdaptorService.invoke(InvokerAdaptorService.java:270)
 at sun.reflect.GeneratedMethodAccessor98.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:157)
 at org.jboss.mx.server.Invocation.dispatch(Invocation.java:96)
 at org.jboss.mx.interceptor.AbstractInterceptor.invoke(AbstractInterceptor.java:138)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:90)
 at org.jboss.mx.interceptor.ModelMBeanOperationInterceptor.invoke(ModelMBeanOperationInterceptor.java:140)
 at org.jboss.jmx.connector.invoker.SerializableInterceptor.invoke(SerializableInterceptor.java:74)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:90)
 at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:668)
 at org.jboss.invocation.jrmp.server.JRMPProxyFactory.invoke(JRMPProxyFactory.java:179)
 at sun.reflect.GeneratedMethodAccessor97.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:157)
 at org.jboss.mx.server.Invocation.dispatch(Invocation.java:96)
 at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
 at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
 at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:668)
 at org.jboss.invocation.jrmp.server.JRMPInvoker$MBeanServerAction.invoke(JRMPInvoker.java:815)
 at org.jboss.invocation.jrmp.server.JRMPInvoker.invoke(JRMPInvoker.java:416)
 at sun.reflect.GeneratedMethodAccessor96.invoke(Unknown Source)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:585)
 at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:294)
 at sun.rmi.transport.Transport$1.run(Transport.java:153)
 at java.security.AccessController.doPrivileged(Native Method)
 at sun.rmi.transport.Transport.serviceCall(Transport.java:149)
 at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:466)
 at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:707)
 at java.lang.Thread.run(Thread.java:595)