Since 2f7b99c780cfdce94b2888ddc8e078536af459a6 we disable all shard version checking while in DBDirectClient. We need to make sure that all operations that use DBDirectClient while operating on sharded collections (maybe just map-reduce?) properly do their own shard versioning handling and weren't relying on shard version checking to happen via DBDirectClient.

As for what the test could look like, I was thinking of something along the line of doing a map-reduce on a stale mongos right after a chunk migration and purposefully creating some orphaned data on the former chunk owner and making sure the map reduce sees the proper data