Merge branch 'rails5-fix-6749' into 'master'

[Rails5] fix NoMethodError: undefined method 'downcase' for Hash

Closes #6749

See merge request gitlab-org/gitlab-ee!6319

ee/changelogs/unreleased/rails5-fix-6749.yml

+---
+title: "[Rails5] fix NoMethodError: undefined method 'downcase' for Hash"
+merge_request: 6319
+author: Jasper Maes
+type: fixed

ee/spec/requests/api/jobs_spec.rb

@@ -32,7 +32,7 @@ describe API::Jobs do
 
       it 'returns specific job artifacts' do
         expect(response).to have_gitlab_http_status(200)
-        expect(response.headers).to include(download_headers)
+        expect(response.headers.to_h).to include(download_headers)
         expect(response.body).to match_file(job.artifacts_file.file.file)
       end
     end