Add explicit variable current encoding

Author: hartator

lib/wayback_machine_downloader.rb

@@ -201,7 +201,8 @@ def structure_dir_path dir_path
   end
 
   def download_file file_remote_info
-    file_url = file_remote_info[:file_url].encode(''.encoding)
+    current_encoding = "".encoding
+    file_url = file_remote_info[:file_url].encode(current_encoding)
     file_id = file_remote_info[:file_id]
     file_timestamp = file_remote_info[:timestamp]
     file_path_elements = file_id.split('/')