Originally, I was thinking _configsvrCreateCommand, _configsvrDropCollection, and _configsvrDropDatabase should send the dbVersion when targeting the primary shard, since a concurrent movePrimary could happen.

Then I realized _configsvrDropCollection and _configsvrDropDatabase already take a database distlock, which movePrimary also takes, and therefore it's not possible for a movePrimary to happen concurrently with these.

So, the easiest thing is to make _configsvrCreateCommand, which targets the primary shard to place the new collection on, also take the database distlock, probably around here.