changing an attribute multiple times retains the correct original value

2 files changed, 10 insertions, 1 deletions

diff --git a/activemodel/lib/active_model/dirty.rb b/activemodel/lib/active_model/dirty.rb
index 3b412d3dd7..166cccf161 100644
--- a/activemodel/lib/active_model/dirty.rb
+++ b/activemodel/lib/active_model/dirty.rb
@@ -156,7 +156,7 @@ module ActiveModel
         rescue TypeError, NoMethodError
         end
 
-        changed_attributes[attr] = value
+        changed_attributes[attr] = value unless changed_attributes.include?(attr)
       end
 
       # Handle <tt>reset_*!</tt> for +method_missing+.
diff --git a/activemodel/test/cases/dirty_test.rb b/activemodel/test/cases/dirty_test.rb
index 858ae9cb69..98244a6290 100644
--- a/activemodel/test/cases/dirty_test.rb
+++ b/activemodel/test/cases/dirty_test.rb
@@ -106,4 +106,13 @@ class DirtyTest < ActiveModel::TestCase
     assert_equal [nil, "Jericho Cane"], @model.previous_changes['name']
   end
 
+  test "changing the same attribute multiple times retains the correct original value" do
+    @model.name = "Otto"
+    @model.save
+    @model.name = "DudeFella ManGuy"
+    @model.name = "Mr. Manfredgensonton"
+    assert_equal ["Otto", "Mr. Manfredgensonton"], @model.name_change
+    assert_equal @model.name_was, "Otto"
+  end
+
 end