Since chain has completed, remove buffer attribute so future error fo…

…rward requests can be buffered.

sitemesh/src/main/java/org/sitemesh/webapp/contentfilter/ContentBufferingFilter.java

@@ -192,6 +192,7 @@ public void preCommit() {
         }
 
         filterChain.doFilter(wrapRequest(request), responseBuffer);
+        request.setAttribute(SITEMESH_BUFFER_ATTRIBUTE, null);
 
         if (request.getAttribute(SITEMESH_DECORATED_ATTRIBUTE) != null) {
             return;