OutputBuffer#to_yaml should return string yaml, not some custom class dump

activesupport/lib/active_support/core_ext/string/output_safety.rb

@@ -88,6 +88,10 @@ def html_safe
     def to_s
       self
     end
+
+    def to_yaml
+      "".replace(self).to_yaml
+    end
   end
 end
 

activesupport/test/core_ext/string_ext_test.rb

@@ -444,6 +444,10 @@ def to_s
     assert_equal "hello".concat(13), string
     assert string.html_safe?
   end
+
+  test 'emits normal string yaml' do
+    assert_equal 'foo'.to_yaml, 'foo'.html_safe.to_yaml
+  end
 end
 
 class StringExcludeTest < ActiveSupport::TestCase