use File.realpath and avoid making Pathname objects

railties/lib/rails/engine.rb

@@ -652,8 +652,7 @@ def find_root_with_flag(flag, default=nil)
       root = File.exist?("#{root_path}/#{flag}") ? root_path : default
       raise "Could not find root path for #{self}" unless root
 
-      RUBY_PLATFORM =~ /mswin|mingw/ ?
-        Pathname.new(root).expand_path : Pathname.new(root).realpath
+      File.realpath root
     end
 
     def default_middleware_stack