Can't pass an array of strings to GitLab API (Build API)

Summary

Can't pass an array of strings to GitLab API: (Builds API: List project builds)

Steps to reproduce

These will be successful:

curl --request GET --header "PRIVATE-TOKEN: ${PRIVATE_TOKEN}" --data 'scope=failed' https://gitlab.com/api/v3/projects/13083/builds
curl --request GET --header "PRIVATE-TOKEN: ${PRIVATE_TOKEN}" --data 'scope=skipped' https://gitlab.com/api/v3/projects/13083/builds

and we'll get some lists.

But these will fail:

curl --request GET --header "PRIVATE-TOKEN: ${PRIVATE_TOKEN}" --data 'scope[]=failed' https://gitlab.com/api/v3/projects/13083/builds
curl --request GET --header "PRIVATE-TOKEN: ${PRIVATE_TOKEN}" --data 'scope[]=failed' --data 'scope[]=skipped' https://gitlab.com/api/v3/projects/13083/builds

and we'll get in both cases:

{"message":"Scope contains invalid value(s)"}

Expected behavior

All cases above should work successfully, in according to the documents doc/api/builds.md#list-project-builds and doc/development/doc_styleguide.md#pass-arrays-to-api-calls.

Actual behavior

As described above.

Appendix

In Build API, scope can be created, pending, running, success, failed, canceled, and skipped. They are defined in app/models/concerns/has_status.rb. But created and skipped are not documented in doc/api/builds.md#list-project-builds.