[rubygems/rubygems] Refactor `Gem.load_path_insert_index`

https://github.com/rubygems/rubygems/commit/ae95885dff

lib/rubygems.rb

@@ -590,7 +590,7 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
 
     index = $LOAD_PATH.index RbConfig::CONFIG['sitelibdir']
 
-    index
+    index || 0
   end
 
   ##
@@ -607,15 +607,8 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
   def self.add_to_load_path(*paths)
     @activated_gem_paths = activated_gem_paths + paths.size
 
-    insert_index = load_path_insert_index
-
-    if insert_index
-      # gem directories must come after -I and ENV['RUBYLIB']
-      $LOAD_PATH.insert(insert_index, *paths)
-    else
-      # we are probably testing in core, -I and RUBYLIB don't apply
-      $LOAD_PATH.unshift(*paths)
-    end
+    # gem directories must come after -I and ENV['RUBYLIB']
+    $LOAD_PATH.insert(Gem.load_path_insert_index, *paths)
   end
 
   @yaml_loaded = false

lib/rubygems/core_ext/kernel_require.rb

@@ -44,10 +44,7 @@ module Kernel
     resolved_path = begin
       rp = nil
       Gem.suffixes.each do |s|
-        load_path_insert_index = Gem.load_path_insert_index
-        break unless load_path_insert_index
-
-        $LOAD_PATH[0...load_path_insert_index - Gem.activated_gem_paths].each do |lp|
+        $LOAD_PATH[0...Gem.load_path_insert_index - Gem.activated_gem_paths].each do |lp|
           safe_lp = lp.dup.tap(&Gem::UNTAINT)
           begin
             if File.symlink? safe_lp # for backward compatibility