If we don't have any clue about a master since it never replied to INFO
so far, reply with an -IDONTKNOW error to SENTINEL
get-master-addr-by-name requests.
ri = sentinelGetMasterByName(c->argv[2]->ptr);
if (ri == NULL) {
addReply(c,shared.nullmultibulk);
+ } else if (ri->info_refresh == 0) {
+ addReplySds(c,sdsnew("-IDONTKNOW I have not enough information to reply. Please ask another Sentinel.\r\n"));
} else {
sentinelAddr *addr = ri->addr;