Fix method_missing delegation to not expand positional hash argument

Follow up to #41518, and similar to 3a85ced1a0.

activesupport/lib/active_support/current_attributes.rb

@@ -155,14 +155,15 @@ module ActiveSupport
           @current_instances_key ||= name.to_sym
         end
 
-        def method_missing(name, *args, **kwargs, &block)
+        def method_missing(name, *args, &block)
           # Caches the method definition as a singleton method of the receiver.
           #
           # By letting #delegate handle it, we avoid an enclosure that'll capture args.
           singleton_class.delegate name, to: :instance
 
-          send(name, *args, **kwargs, &block)
+          send(name, *args, &block)
         end
+        ruby2_keywords(:method_missing) if respond_to?(:ruby2_keywords, true)
 
         def respond_to_missing?(name, _)
           super || instance.respond_to?(name)

activesupport/test/current_attributes_test.rb

@@ -36,6 +36,12 @@ class CurrentAttributesTest < ActiveSupport::TestCase
       self.account = account
     end
 
+    def get_world_and_account(hash)
+      hash[:world] = world
+      hash[:account] = account
+      hash
+    end
+
     def respond_to_test; end
 
     def request
@@ -138,6 +144,11 @@ class CurrentAttributesTest < ActiveSupport::TestCase
 
     assert_equal "world/1", Current.world
     assert_equal "account/1", Current.account
+
+    hash = {}
+    assert_same hash, Current.get_world_and_account(hash)
+    assert_equal "world/1", hash[:world]
+    assert_equal "account/1", hash[:account]
   end
 
   setup { @testing_teardown = false }