AbstractConversationContext.deactivate() throws ConcurrentModificationException

I try to use a Conversation in JBossAS 6.0.1 Hudson build 2296 which contains Weld 1.1.0. However, I get the following stacktrace:

16:05:31,795 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/swe2].[FacesServlet]] Servlet.service() for servlet FacesServlet threw exception: java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextEntry(HashMap.java:793) [:1.6.0_23]
at java.util.HashMap$EntryIterator.next(HashMap.java:834) [:1.6.0_23]
at java.util.HashMap$EntryIterator.next(HashMap.java:832) [:1.6.0_23]
at org.jboss.weld.context.AbstractConversationContext.deactivate(AbstractConversationContext.java:250) [:6.0.1-SNAPSHOT]
at org.jboss.weld.jsf.WeldPhaseListener.deactivateConversations(WeldPhaseListener.java:131) [:6.0.1-SNAPSHOT]
at org.jboss.weld.jsf.WeldPhaseListener.afterPhase(WeldPhaseListener.java:92) [:6.0.1-SNAPSHOT]
at com.sun.faces.lifecycle.Phase.handleAfterPhase(Phase.java:185) [:2.0.3-]
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:103) [:2.0.3-]
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:135) [:2.0.3-]
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:309) [:2.0.3-]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:324) [:]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:]
at org.jboss.weld.servlet.ConversationPropagationFilter.doFilter(ConversationPropagationFilter.java:67) [:6.0.1-SNAPSHOT]
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:274) [:]
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:242) [:]
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:275) [:]
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191) [:]
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:181) [:6.0.1-SNAPSHOT]
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501) [:]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.event(CatalinaContext.java:285) [:1.1.0.Final]
at org.jboss.modcluster.catalina.CatalinaContext$RequestListenerValve.invoke(CatalinaContext.java:261) [:1.1.0.Final]
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:88) [:6.0.1-SNAPSHOT]
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:100) [:6.0.1-SNAPSHOT]
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127) [:]
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102) [:]
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158) [:6.0.1-SNAPSHOT]
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109) [:]
at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.invoke(ActiveRequestResponseCacheValve.java:53) [:6.0.1-SNAPSHOT]
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:362) [:]
at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcessor.java:893) [:]
at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.process(Http11AprProtocol.java:600) [:]
at org.apache.tomcat.util.net.AprEndpoint$Worker.run(AprEndpoint.java:2019) [:]
at java.lang.Thread.run(Thread.java:662) [:1.6.0_23]