Retry each op if PB client get {error,disconnected}

The ProtoBuffs client is using {auto_reconnect,true}. The PB client pid remains alive as a middle-man process, but it can send {error,disconnected} to its user.  If that happens, retry the op.  Given the current code shape, it isn't possible to reuse the same generated key & value; our retry will regenerate new ones.