Fix `ActionController::Parameters#==` bug

See bug #21032.

actionpack/CHANGELOG.md

+*   Fix `ActionController::Parameters==`
+
+   *Jon Moss*
+
 *   Response etags to always be weak: Prefixes 'W/' to value returned by
    `ActionDispatch::Http::Cache::Response#etag=`, such that etags set in
    `fresh_when` and `stale?` are weak.

actionpack/lib/action_controller/metal/strong_parameters.rb

@@ -160,7 +160,11 @@ def ==(other_hash)
       if other_hash.respond_to?(:permitted?)
         super
       else
-        @parameters == other_hash
+        if other_hash.is_a?(Hash)
+          @parameters == other_hash.with_indifferent_access
+        else
+          @parameters == other_hash
+        end
       end
     end
 

actionpack/test/controller/parameters/accessors_test.rb

@@ -128,4 +128,10 @@ class ParametersAccessorsTest < ActiveSupport::TestCase
     assert_not @params.values_at(:person).first.permitted?
     assert_not @params[:person].values_at(:name).first.permitted?
   end
+
+  test "equality with another hash works" do
+    hash1 = { foo: :bar }
+    params1 = ActionController::Parameters.new(hash1)
+    assert(params1 == hash1)
+  end
 end