A bit late to the party, but I just tried #12653 and noticed some non-intuitive behavior (on macOS), that's probably worth explaining release notes and help.

Before this new feature I kept the entire datadir on an SSD drive, so I launch with: `bitcoind -datadir=/Volumes/SSD/Bitcoin`.

Initially I naively moved `/Volumes/SSD/Bitcoin/blocks` to `/Users/bitcoin/blocks` and added a line to `/Volumes/SSD/Bitcoin/bitcoin.conf`: `blocksdir=/Users/bitcoin/blocks`.

I then realized that I shouldn't have moved the `index` subdirectory, so I moved that back to `/Volumes/SSD/Bitcoin/blocks/index`. Having an empty `blocks` dir with just and `index` subdir is a bit weird. Perhaps after @jimpo's #11857 is merged, we could just move / assume all indexes to be there (if `-blocksdir` is set)?

Worse, it created a directory `/Users/bitcoin/blocks/blocks`, which seems like a bug. I had to set `blocksdir=/Users/bitcoin` instead.
{
    StartShutdown();
    Sleep(INFINITE);
    return true;
}
#endif
#ifndef WIN32
static void registerSignalHandler(int signal, void(*handler)(int))
{
    struct sigaction sa;
    sa.sa_handler = handler;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = 0;
    sigaction(signal, &sa, nullptr);
}
#endif
static void OnRPCStarted()
{
    uiInterface.NotifyBlockTip_connect(&RPCNotifyBlockChange);
}
static void OnRPCStopped()
{
    uiInterface.NotifyBlockTip_disconnect(&RPCNotifyBlockChange);
    RPCNotifyBlockChange(false, nullptr);
    g_best_block_cv.notify_all();
    LogPrint(BCLog::RPC, "RPC stopped.\n");
}
void SetupServerArgs()