[rubygems/rubygems] Remove outdated/incorrect comment.

The function is also significantly simpler than it used to be,
to the point I'm not sure it needs a comment.

https://github.com/rubygems/rubygems/commit/29a0551e37

lib/rubygems/path_support.rb

@@ -56,10 +56,6 @@ class Gem::PathSupport
 
   private
 
-  ##
-  # The default home directory.
-  # This function was broken out to accommodate tests in `bundler/spec/commands/doctor_spec.rb`.
-
   def normalize_home_dir(home)
     if File::ALT_SEPARATOR
       home = home.gsub(File::ALT_SEPARATOR, File::SEPARATOR)