--- server/util_filter.c	(revision 291602)
+++ server/util_filter.c	(working copy)
@@ -578,8 +578,18 @@ 
                                                 void *ctx)
 {
     ap_filter_t *f = ctx;
+    apr_status_t rv;
 
-    return ap_pass_brigade(f, bb);
+    rv = ap_pass_brigade(f, bb);
+
+    /* apr_brigade_write* require that the flush function ensures that
+     * the brigade is empty upon return; otherwise the brigade may be
+     * left with a transient bucket whose contents have fallen out of
+     * scope.  Call cleanup here unconditionally to avoid the issue in
+     * all cases. */
+    apr_brigade_cleanup(bb);
+
+    return rv;
 }
 
 AP_DECLARE(apr_status_t) ap_fflush(ap_filter_t *f, apr_bucket_brigade *bb)