`RewindBlockIndex` was made to allow nodes upgrading to new consensus rules post-segwit fork to 
download new consensus data (i.e witnesses) without having to go through a whole IBD. It has been pointed than now really few pre-segwit nodes care to upgrade and that this logic may be irrelevant.

See https://github.com/bitcoin/bitcoin/pull/17737#discussion_r358514335 in review  of #17737 for more context pointers.
}
        
        
        
        if (nConflictingCount <= maxDescendantsToVisit) {
            
            
            for (CTxMemPool::txiter it : setIterConflicting) {
                m_pool.CalculateDescendants(it, allConflicting);
            }
            for (CTxMemPool::txiter it : allConflicting) {
                nConflictingFees += it->GetModifiedFee();
                nConflictingSize += it->GetTxSize();
            }
        } else {
            return state.Invalid(TxValidationResult::TX_MEMPOOL_POLICY, "too many potential replacements",
                    strprintf("rejecting replacement %s; too many potential replacements (%d > %d)\n",
                        hash.ToString(),
                        nConflictingCount,
                        maxDescendantsToVisit));
        }
        for (unsigned int j = 0; j < tx.vin.size(); j++)
        {