This is to track the regression introduced in master, which needs fixing for 0.14. See #9240, #9371, etc.
setEntries setChildren;
        
        txiter it = mapTx.find(hash);
        if (it == mapTx.end()) {
            continue;
        }
        auto iter = mapNextTx.lower_bound(COutPoint(hash, 0));
        
        
        for (; iter != mapNextTx.end() && iter->first->hash == hash; ++iter) {
            const uint256 &childHash = iter->second->GetHash();
            txiter childIter = mapTx.find(childHash);
            assert(childIter != mapTx.end());
            
            
            if (setChildren.insert(childIter).second && !setAlreadyIncluded.count(childHash)) {
                UpdateChild(it, childIter, true);
                UpdateParent(childIter, it, true);
            }
        }
        UpdateForDescendants(it, mapMemPoolDescendantsToUpdate, setAlreadyIncluded);
    }
}
bool CTxMemPool::CalculateMemPoolAncestors(const CTxMemPoolEntry &entry, setEntries &setAncestors, uint64_t limitAncestorCount, uint64_t limitAncestorSize, uint64_t limitDescendantCount, uint64_t limitDescendantSize, std::string &errString, bool fSearchForParents ) const