Improve readablity of CI_API_V4_URL related code

app/models/project.rb

@@ -1705,9 +1705,7 @@ class Project < ActiveRecord::Base
 
   def api_variables
     Gitlab::Ci::Variables::Collection.new.tap do |variables|
-      API::Helpers::Version.new('v4').tap do |version|
-        variables.append(key: 'CI_API_V4_URL', value: version.root_url)
-      end
+      variables.append(key: 'CI_API_V4_URL', value: API::Helpers::Version.new('v4').root_url)
     end
   end
 

spec/lib/api/helpers/version_spec.rb

@@ -20,7 +20,7 @@ describe API::Helpers::Version do
   describe '#root_url' do
     it 'returns an URL for a root path for the API version' do
       expect(described_class.new('v4').root_url)
-        .to match %r{^http?://.*/api/v4$}
+        .to eq 'http://localhost/api/v4'
     end
   end
 end