// Check if the target namespace exists and if dropTarget is true.
    // Return a non-OK status if target exists and dropTarget is not true or if the collection
    // is sharded.
    Collection* targetColl = targetDB->getCollection(opCtx, target);
    if (targetColl) {
        // If we already have the collection with the target UUID, we found our future selves,
        // so nothing left to do but drop the source collection in case of cross-db renames.
        if (targetUUID && targetUUID == targetColl->uuid()) {
            if (source.db() == target.db())
                return Status::OK();
            BSONObjBuilder unusedResult;
            return dropCollection(opCtx,
                                  source,
                                  unusedResult,
                                  {},
                                  DropCollectionSystemCollectionMode::kAllowSystemCollectionDrops);
        }