Add comments to r39808
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39816 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
Add comments to r39808
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39816 b2dd03c8-39d4-4d8f-98ff-823fe69b080e