On a mongod, running a $collStats aggregation on a nonexistent database returns a basic document with information about the namespace, the host's ip, and the local machine's time. Otherwise it returns no data about the nonexistent collection. On mongos, the same aggregation results in an error.

The goal of this ticket is to unify the behavior. It is an open question what the result operation should include: host and localTime may not make sense in a mongos context as it may be routing between potentially multiple shards.