Index: modules/http/http_request.c
===================================================================
--- modules/http/http_request.c	(revision 952555)
+++ modules/http/http_request.c	(working copy)
@@ -460,17 +460,47 @@
     new->proto_output_filters  = r->proto_output_filters;
     new->proto_input_filters   = r->proto_input_filters;
 
-    new->output_filters  = new->proto_output_filters;
     new->input_filters   = new->proto_input_filters;
 
     if (new->main) {
-        /* Add back the subrequest filter, which we lost when
-         * we set output_filters to include only the protocol
-         * output filters from the original request.
-         */
-        ap_add_output_filter_handle(ap_subreq_core_filter_handle,
-                                    NULL, new, new->connection);
+        ap_filter_t *f, *nextf;
+
+        /* If this is a subrequest, the filter chain may contain a
+         * mixture of filters specific to the old request (r), and
+         * some inherited from r->main.  Here, inherit that filter
+         * chain, and remove all those which are specific to the old
+         * request; ensuring the subreq filter is left in place. */
+        new->output_filters = r->output_filters;
+
+        f = new->output_filters;
+        do {
+            nextf = f->next;
+
+            if (f->r == r && f->frec != ap_subreq_core_filter_handle) {
+                ap_log_rerror(APLOG_MARK, APLOG_DEBUG, 0, r,
+                              "dropping filter '%s' in internal redirect from %s to %s",
+                              f->frec->name, r->unparsed_uri, new_uri);
+
+                /* To remove the filter, first set f->r to the *new*
+                 * request_rec, so that ->output_filters on 'new' is
+                 * changed (if necessary) when removing the filter. */
+                f->r = new;
+                ap_remove_output_filter(f);
+            }
+
+            f = nextf;
+
+            /* Stop at the protocol filters.  If a protocol filter has
+             * been newly installed for this resource, better leave it
+             * in place, though it's probably a misconfiguration or
+             * filter bug to get into this state. */
+        } while (f && f != new->proto_output_filters);
     }
+    else {
+        /* If this is not a subrequest, clear out all
+         * resource-specific filters. */
+        new->output_filters  = new->proto_output_filters;
+    }
 
     update_r_in_filters(new->input_filters, r, new);
     update_r_in_filters(new->output_filters, r, new);