Comment 1 for bug 1616636

Alternatively, the board parameter - though it is being parsed as a URL - is not really used in that way and you're actually supposed to always parse the redis URL yourself and pass in the host and port parameters to fetch_backend. In that case, might I recommend that `fetch_backend` rejects a URL and only allows one of `zookeeper` or `redis` ? Would have helped me diagnose this problem more readily.