The oplog code for applyOperation_inLock for applying OpTypeEnum::kDelete operation on secondaries currently contains this code comment:

// It is legal for a delete operation on the pre-images collection to delete
// zero documents - pre-image collections are not guaranteed to contain the same
// set of documents at all times. The same holds for change-collections as they
// both rely on unreplicated deletes.

This comment will become obsolete with replicated truncates on the pre-images collection and should be adjusted.
Also there should not be any more individual deletes on the pre-images collection at all on secondaries, as documents in the pre-images collection are not deleted one by one, but via truncates.