anchor.diff:            ..lastStatus = status
             ..processingKey = null
             ..errorCount = errorCount
  -          ..lockedUntil =
  -              new DateTime.now().toUtc().add(extendDuration ?? _extendDuration)
  +          ..lockedUntil = _extendLock(errorCount, duration: extendDuration)
             ..updatePriority();
           tx.queueMutations(inserts: [selected]);
           await tx.commit();
  
positive.code:       },
      };
    }
  }
  
negative.code:       final list = await tx.lookup([_db.emptyKey.append(Job, id: id)]);
        final current = list.single as Job;
        if (current != null) {
          final hasNotChanged = current.isLatestStable == isLatestStable &&
              current.packageVersionUpdated == packageVersionUpdated &&
              current.runtimeVersion == versions.runtimeVersion;
          if (hasNotChanged) {
            if (!shouldProcess) {
              // no reason to re-schedule to job
              return;
            } else if (current.errorCount > 0) {
              // prevent untimely re-try of a failed job
              return;
            }
          }
          if (isNewer(
              versions.semanticRuntimeVersion, current.semanticRuntimeVersion)) {
            // a new instance has already updated the Job with new runtimeVersion
            return;
          }
          _logger.info('Updating job: $id');
  