`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 (!SetupNetworking()) {
        return InitError(Untranslated("Initializing networking failed."));
    }
#ifndef WIN32
    if (!args.GetBoolArg("-sysperms", false)) {
        umask(077);
    }
    
    registerSignalHandler(SIGTERM, HandleSIGTERM);
    registerSignalHandler(SIGINT, HandleSIGTERM);
    
    registerSignalHandler(SIGHUP, HandleSIGHUP);
    
    signal(SIGPIPE, SIG_IGN);
#else
    SetConsoleCtrlHandler(consoleCtrlHandler, true);
#endif
    std::set_new_handler(new_handler_terminate);
    return true;
}
bool AppInitParameterInteraction(const ArgsManager& args)
{
    const CChainParams& chainparams = Params();
    
    
    
    
    
    std::string network = args.GetChainName();
    if (network == CBaseChainParams::SIGNET) {