diff -r ea3d443fb6bc -r 3c36683e13be servlib/bundling/BPQResponse.cc
--- a/servlib/bundling/BPQResponse.cc	Wed Jun 29 13:09:12 2011 +0100
+++ b/servlib/bundling/BPQResponse.cc	Thu Jun 30 13:13:10 2011 +0100
@@ -75,9 +75,16 @@
                              buf(current_bi.full_length())
                            + current_bi.data_offset();
 
-        BlockInfo* new_bi = new_response->api_blocks()->append_block(new_bp);
+        // it is intentional that the blocks are copied from 
+        // the api -> recv list
+        // API blocks should not exist before a bundle is sent 
+        // and will break an assertion in 
+        // bundling/PrimaryBlockProcessor.cc:
+        // ASSERTION FAILED (xmit_blocks->size() == 0) 
+        BlockInfo* new_bi = new_response->mutable_recv_blocks()->
+                            append_block(new_bp);
         new_bp->init_block( new_bi,
-                            new_response->api_blocks(),
+                            new_response->mutable_recv_blocks(),
                             current_bi.type(),
                             current_bi.flags(),
                             data,