jstests/sharding/retryable_internal_transaction_test.js runs several test cases with a transaction larger than 16MB and loads the oplog entries generated by those tests for its assertions. If the oplog is truncated while the test is reading from it, the query will fail with CappedPositionLost and fail the test. Each test case only needs the oplog entries from the most recent large transaction, so it should be safe to retry on this error since the necessary oplog entries were likely not truncated.