Some tests like authCommands.js insert some documents and then call moveChunk, expecting the autosplitter to have run. With the new autosplitting behavior, splitting is asynchronous, so it won't necessarily have completed in between the inserts and the moveChunk, so the moveChunk will fail because the chunk will be too large. These tests are not intentionally testing this autosplitter behavior, so they shouldn't rely on it. In cases like these we should call the splitChunk command manually.