SERVER-17397 has been fixed in since 5.0 and thus there is no need to run the dropDatabase command twice on the mongos anymore.

We should modify the documentation of both:

• dropDatabase command
• db.dropDatabase() helper method

In paritcular in both of them we have the following statement.

For MongoDB 4.4 and later, you must:

1. Run the dropDatabase command on a mongos.
2. Once the command successfully completes, run the dropDatabase command once more on a mongos.

Since 5.0 step 2 is no longer required and can be removed.