ThreadLocal is not cleaned when an exception occurs in ExceptionFilter.endWebRequestAfterException

org.jboss.seam.ConcurrentRequestTimeoutException: Concurrent call to conversation
    at org.jboss.seam.core.Manager.restoreAndLockConversation(Manager.java:641)
    at org.jboss.seam.core.Manager.restoreConversation(Manager.java:603)
->    at org.jboss.seam.web.ExceptionFilter.endWebRequestAfterException(ExceptionFilter.java:107)

java.lang.NullPointerException
	at org.jboss.web.tomcat.service.session.JBossCacheManager.loadSession(JBossCacheManager.java:2096)
	at org.jboss.web.tomcat.service.session.JBossCacheManager.findSession(JBossCacheManager.java:595)
	at org.apache.catalina.connector.Request.doGetSession(Request.java:2351)
	at org.apache.catalina.connector.Request.getSession(Request.java:2094)
	at org.apache.catalina.connector.RequestFacade.getSession(RequestFacade.java:833)
	at org.jboss.seam.mock.MockExternalContext.getSessionMap(MockExternalContext.java:357)
	at org.jboss.seam.contexts.FacesLifecycle.beginExceptionRecovery(FacesLifecycle.java:86)
->	at org.jboss.seam.web.ExceptionFilter.endWebRequestAfterException(ExceptionFilter.java:96)

 74#   protected void endWebRequestAfterException(HttpServletRequest request, HttpServletResponse response, Exception e) 
 75#         throws ServletException, IOException
 76#   {
 77#      
 78#      log.debug("running exception handlers");
 79#      
 80#      //if the event context was cleaned up, fish the conversation id 
 81#      //directly out of the ServletRequest attributes, else get it from
 82#      //the event context
 83#      Manager manager = Contexts.isEventContextActive() ?
 84#              (Manager) Contexts.getEventContext().get(Manager.class) :
 85#              (Manager) request.getAttribute( Seam.getComponentName(Manager.class) );
 86#      String conversationId = manager==null ? null : manager.getCurrentConversationId();
 87#      
 88#      // Ensure that the call in which the exception occurred was cleaned up - it might not be, and there is no harm in trying
 89#      Lifecycle.endRequest();
 90#      
 91#      //the FacesContext is gone - create a fake one for Redirect and HttpError to call
 92#      MockFacesContext facesContext = createFacesContext(request, response);
 93#      facesContext.setCurrent();
 94#      
 95#      //Initialize the temporary context objects
-> 96#      FacesLifecycle.beginExceptionRecovery( facesContext.getExternalContext() );
 97#      
 98#      //If there is an existing long-running conversation on
 99#      //the failed request, propagate it
100#      if (conversationId==null)
101#      {
102#          Manager.instance().initializeTemporaryConversation();
103#      }
104#      else
105#      {
106#          ConversationPropagation.instance().setConversationId(conversationId);
->107#          Manager.instance().restoreConversation();
108#      }
109#      
110#      //Now do the exception handling
111#      try
112#      {
113#         rollbackTransactionIfNecessary();
114#         Exceptions.instance().handle(e);
115#      }
116#      catch (ServletException se)
117#      {
118#         throw se;
119#      }
120#      catch (IOException ioe)
121#      {
122#         throw ioe;
123#      }
124#      catch (Exception ehe)
125#      {
126#         throw new ServletException(ehe);
127#      }
128#      finally
129#      {
130#         //Finally, clean up the contexts
131#         try 
132#         {
->133#            FacesLifecycle.endRequest( facesContext.getExternalContext() );
134#            facesContext.release();
135#            log.debug("done running exception handlers");
136#         }
137#         catch (Exception ere)
138#         {
139#            log.error("could not destroy contexts", ere);
140#         }
141#      }
142#   }