// Add IDs to bundle.feeds

db.bundles.find().forEach(function (b) {
  b.feeds.forEach(function (f) { f.id = f.feedId + '_' + b._id })
  db.bundles.save(b)
})
// Add IDs to bundle.feeds

db.bundles.find().forEach(function (b) {
  if (b.feeds != null) {
    b.feeds.forEach(function (f) { f.id = f.feedId + '_' + b._id })
    db.bundles.save(b)
  }
})
check for null feeds before migrating bundle.