mutate the path string to avoid object allocations

actionpack/lib/action_dispatch/http/url.rb

@@ -45,14 +45,14 @@ def url_for(options)
 
           if options[:trailing_slash]
             if path.include?('?')
-              result << path.sub(/\?/, '/\&')
+              path.sub!(/\?/, '/\&')
             else
-              result << path.sub(/[^\/]\z|\A\z/, '\&/')
+              path.sub!(/[^\/]\z|\A\z/, '\&/')
             end
-          else
-            result << path
           end
 
+          result << path
+
           if options.key? :params
             params = options[:params].is_a?(Hash) ?
                                  options[:params] :