`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.
{
    
    
    
    
    std::set_new_handler(std::terminate);
    LogPrintf("Error: Out of memory. Terminating.\n");
    
    std::terminate();
};
bool AppInitBasicSetup(const ArgsManager& args)
{
    
#ifdef _MSC_VER
    
    _CrtSetReportMode(_CRT_WARN, _CRTDBG_MODE_FILE);
    _CrtSetReportFile(_CRT_WARN, CreateFileA("NUL", GENERIC_WRITE, 0, nullptr, OPEN_EXISTING, 0, 0));
    
    _set_abort_behavior(0, _WRITE_ABORT_MSG | _CALL_REPORTFAULT);
#endif
#ifdef WIN32
    
    HeapSetInformation(nullptr, HeapEnableTerminationOnCorruption, nullptr, 0);
#endif
    if (!InitShutdownState()) {
        return InitError(Untranslated("Initializing wait-for-shutdown state failed."));
    }