Problem Statement

Dropping a collection directly from a shard on a sharded cluster is not a supported action. If one drops a collection directly while a migration is happening for that collection, issues can arise. Such as the following:

If a collection/db is dropped from the recipient shard after it finishes cloning from the donor shard, it's possible that the migration still commits. The config will still think the recipient shard owns the chunk from the migration, but the shard will not know about the collection at all.

Fix

Change the linked test to drop the collection against the mongos instead of the shard.