In the prepare_transaction_then_migrate.js test there is a stepUp and then a migration in a parallel shell which is expected to hang in a point in the migration. However, if the source shard is still executing the step up process then the migration will fail with a NotWritablePrimary error, causing the test to time out waiting for a migration to get into a point that will never reach.

We could either retry the moveChunk command or find a way to wait for the primary to reach a steady state.