[rubygems/rubygems] call key.to_s once instead of multiple times to save when it's a symbol

https://github.com/rubygems/rubygems/commit/535feb817c

lib/bundler/settings.rb

@@ -412,6 +412,8 @@ module Bundler
     end
 
     def converted_value(value, key)
+      key = key.to_s
+
       if is_array(key)
         to_array(value)
       elsif value.nil?