message: Remove experimental logic to make revision comments be
  JSON-encoded objects. Comments are just strings.
diff: @@ -1510,17 +1510,10 @@ export class TxnManager {
  let txnId = this.queryFirstTxnId();
  while (this.isTxnIdValid(txnId)) {
  - const txnDescStr = this.getTxnDescription(txnId);
  - if ((txnDescStr.length === 0) || seen.has(txnDescStr))
  + const txnDesc = this.getTxnDescription(txnId);
  + if ((txnDesc.length === 0) || seen.has(txnDesc))
  continue;
  - let txnDesc: any;
  - try {
  - txnDesc = JSON.parse(txnDescStr);
  - } catch (err) {
  - txnDesc = { description: txnDescStr };
  - }
  -
  changes.push(txnDesc);
  seen.add(txnDesc);
  txnId = this.queryNextTxnId(txnId);
  