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.
return false;
                }
            } else {
                return InitError(strLoadError);
            }
        }
    }
    
    
    
    if (ShutdownRequested()) {
        LogPrintf("Shutdown requested. Exiting.\n");
        return false;
    }
    fs::path est_path = GetDataDir() / FEE_ESTIMATES_FILENAME;
    CAutoFile est_filein(fsbridge::fopen(est_path, "rb"), SER_DISK, CLIENT_VERSION);
    
    if (!est_filein.IsNull())
        ::feeEstimator.Read(est_filein);
    fFeeEstimatesInitialized = true;
    
    if (gArgs.GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
        g_txindex = MakeUnique<TxIndex>(nTxIndexCache, false, fReindex);
        g_txindex->Start();
    }
    
    if (!g_wallet_init_interface.Open()) return false;