Update Active Model xml serialization test to reflect a change in builder

Due to a change in builder, nil values and empty strings now generates
closed tags, so instead of this:

    <pseudonyms nil=\"true\"></pseudonyms>

It generates this:

    <pseudonyms nil=\"true\"/>

Document this change in Rails so that people can track it down easily if
necessary.

Conflicts:
	activemodel/CHANGELOG.md

1 files changed, 1 insertions, 1 deletions

diff --git a/activemodel/test/cases/serializers/xml_serialization_test.rb b/activemodel/test/cases/serializers/xml_serialization_test.rb
index 38aecf51ff..7f14b21cf4 100644
--- a/activemodel/test/cases/serializers/xml_serialization_test.rb
+++ b/activemodel/test/cases/serializers/xml_serialization_test.rb
@@ -132,7 +132,7 @@ class XmlSerializationTest < ActiveModel::TestCase
   end
 
   test "should serialize nil" do
-    assert_match %r{<pseudonyms nil=\"true\"></pseudonyms>}, @contact.to_xml(:methods => :pseudonyms)
+    assert_match %r{<pseudonyms nil=\"true\"/>}, @contact.to_xml(:methods => :pseudonyms)
   end
 
   test "should serialize integer" do