Rack 3 update: Fix headers handling

Author: jochenehret

spec/request/packages_spec.rb

@@ -1194,7 +1194,7 @@
 
       expect(last_response.status).to eq(202)
       expect(last_response.body).to eq('')
-      expect(last_response.header['Location']).to match(%r{jobs/[a-fA-F0-9-]+})
+      expect(last_response.headers['Location']).to match(%r{jobs/[a-fA-F0-9-]+})
       execute_all_jobs(expected_successes: 2, expected_failures: 0)
       get "/v3/packages/#{guid}", {}, user_header
       expect(last_response.status).to eq(404)

spec/unit/controllers/v3/application_controller_spec.rb

@@ -362,7 +362,7 @@ def warnings_incorrect_type
       routes.draw { get 'multiple_warnings' => 'anonymous#multiple_warnings' }
       get :multiple_warnings
       expect(response).to have_http_status(:ok)
-      warnings = response.headers['X-Cf-Warnings'].split(',').map { |w| CGI.unescape(w) }
+      warnings = response.headers['X-Cf-Warnings'].map { |w| CGI.unescape(w) }
       expect(warnings).to eq([
         'warning,a',
         'wa,rning b',