`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.
hash.ToString(),
                        FormatMoney(nDeltaFees),
                        FormatMoney(::incrementalRelayFee.GetFee(nSize))));
        }
    }
    return true;
}
bool MemPoolAccept::PolicyScriptChecks(const ATMPArgs& args, Workspace& ws, PrecomputedTransactionData& txdata)
{
    const CTransaction& tx = *ws.m_ptx;
    TxValidationState& state = ws.m_state;
    constexpr unsigned int scriptVerifyFlags = STANDARD_SCRIPT_VERIFY_FLAGS;
    
    
    if (!CheckInputScripts(tx, state, m_view, scriptVerifyFlags, true, false, txdata)) {
        
        
        
        TxValidationState state_dummy; 
        if (!tx.HasWitness() && CheckInputScripts(tx, state_dummy, m_view, scriptVerifyFlags & ~(SCRIPT_VERIFY_WITNESS | SCRIPT_VERIFY_CLEANSTACK), true, false, txdata) &&
                !CheckInputScripts(tx, state_dummy, m_view, scriptVerifyFlags & ~SCRIPT_VERIFY_CLEANSTACK, true, false, txdata)) {
            
            state.Invalid(TxValidationResult::TX_WITNESS_STRIPPED,
                    state.GetRejectReason(), state.GetDebugMessage());
        }
        return false; 
    }
    return true;
}
bool MemPoolAccept::ConsensusScriptChecks(const ATMPArgs& args, Workspace& ws, PrecomputedTransactionData& txdata)