[rubygems/rubygems] Added explicitly loading for Gem::SafeYAML

https://github.com/rubygems/rubygems/commit/3d9d587dd7

lib/rubygems/gemcutter_utilities.rb

@@ -332,6 +332,8 @@ module Gem::GemcutterUtilities
       request.basic_auth email, password
     end
 
+    Gem.load_yaml
+
     with_response response do |resp|
       Gem::SafeYAML.load clean_text(resp.body)
     end