This was adding the op right back onto the node that it just attempted to redistribute away from, and then letting the op go down into the next set of logic to be cloned and redistributed doubly, instead of adding the operation with it's key to get a new node and then returning. 
introduced here: https://github.com/couchbase/spymemcached/commit/e6892a075fa6f018d9b224bce11a1292263cae8b