(Sorry for the broken threading. I didn't have a convenient copy of the original message to reply to.)
I looked at the patch and it seems quite reasonable, but two hunks of the changes to src/backend/commands/cluster.c don't apply cleanly. I'm not sure what version the patch was generated against, but the code in copy_heap_data() seems to have changed quite a bit. I don't think it would be too much trouble to adapt the changes, though.