The unit test CleanUpForMigrateIn checks the number of ranges to clean after waiting for the future returned by beginReceive to finish. However, the range is only removed after an asynchronous callback is completed. This creates a race condition in this test between the assertion that there are no ranges to clean and the deletion of the range deletion task from the list.

The test is not actually using the assertions causing the problem, so the solution is simply to remove them.