Added comments for extended require by RubyGems

lib/rubygems/core_ext/kernel_require.rb

@@ -36,11 +36,13 @@ module Kernel
 
     path = path.to_path if path.respond_to? :to_path
 
+    # Ensure -I beats a default gem
+    # https://github.com/rubygems/rubygems/pull/1868
     resolved_path = begin
       rp = nil
       $LOAD_PATH[0...Gem.load_path_insert_index].each do |lp|
         safe_lp = lp.dup.untaint
-        next if File.symlink? safe_lp
+        next if File.symlink? safe_lp # for backword compatibility
         Gem.suffixes.each do |s|
           full_path = File.expand_path(File.join(safe_lp, "#{path}#{s}"))
           if File.file?(full_path)