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.
"This may be due to your computer's date and time being set incorrectly. "
                                "Only rebuild the block database if you are sure that your computer's date and time are correct");
                        break;
                    }
                    if (!CVerifyDB().VerifyDB(chainparams, pcoinsdbview.get(), gArgs.GetArg("-checklevel", DEFAULT_CHECKLEVEL),
                                  gArgs.GetArg("-checkblocks", DEFAULT_CHECKBLOCKS))) {
                        strLoadError = _("Corrupted block database detected");
                        break;
                    }
                }
            } catch (const std::exception& e) {
                LogPrintf("%s\n", e.what());
                strLoadError = _("Error opening block database");
                break;
            }
            fLoaded = true;
            LogPrintf(" block index %15dms\n", GetTimeMillis() - load_block_index_start_time);
        } while(false);
        if (!fLoaded && !ShutdownRequested()) {
            
            if (!fReset) {
                bool fRet = uiInterface.ThreadSafeQuestion(
                    strLoadError + ".\n\n" + _("Do you want to rebuild the block database now?"),
                    strLoadError + ".\nPlease restart with -reindex or -reindex-chainstate to recover.",
                    "", CClientUIInterface::MSG_ERROR | CClientUIInterface::BTN_ABORT);
                if (fRet) {
                    fReindex = true;
                    AbortShutdown();
                } else {
                    LogPrintf("Aborted block database rebuild. Exiting.\n");