Clone Problem Failed

[nichujie]

Swagger request:

curl -X 'POST' \
  'http://nichujie.xyz/api/v1/domains/markdown-test/problems/clone' \
  -H 'accept: application/json' \
  -H 'Content-Type: application/json' \
  -d '{
  "problems": [
    "5395c764-3790-4979-8f92-d35e5012ef33"
  ],
  "problemSet": "892bca3f-6921-4794-a1ec-2c359d595c48",
  "newGroup": false
}'

Rollbar: https://rollbar.com/sjtu/horse/items/16/?utm_campaign=new_item_message&utm_medium=slack&utm_source=rollbar-notification

[nichujie]

TODO: transaction