The initial_sync_multiversion_fuzzer and rollback_multiversion_fuzzer both exercise randomized rollbacks and initial syncs in replica sets with random assignments of mixed binary versions. This test coverage seems to supersede the existing, basic tests we have for mixed version initial sync and rollback:

• initial_sync_last_stable_from_latest.js
• initial_sync_latest_from_last_stable.js
• rollback_last_stable_to_latest.js
• rollback_latest_to_last_stable.js

We should be able to delete these obsolete tests in favor of the more thorough and general coverage given by the fuzzer suites.