Do not consider the numeric attribute as changed if the old value is

zero and the new value is not a string.

Before this commit this was the behavior

r = Review.find_by_issue(0)
r.issue
=> 0
r.changes
=> {}
r.issue = 0
=> 0
r.changed?
=> true
r.changes
=> {"issue"=>[0,0]}

Fixes rails#7237

activerecord/CHANGELOG.md

@@ -1,5 +1,11 @@
 ## Rails 3.2.8 ##
 
+*   Do not consider the numeric attribute as changed if the old value is zero and the new value
+    is not a string.
+    Fixes #7237.
+
+    *Rafael Mendonça França*
+
 *   Removes the deprecation of `update_attribute`. *fxn*
 
 *   Reverted the deprecation of `composed_of`. *Rafael Mendonça França*

activerecord/lib/active_record/attribute_methods/dirty.rb

@@ -104,7 +104,7 @@ def changes_from_nil_to_empty_string?(column, old, value)
 
       def changes_from_zero_to_string?(old, value)
         # For columns with old 0 and value non-empty string
-        old == 0 && value.present? && value != '0'
+        old == 0 && value.is_a?(String) && value.present? && value != '0'
       end
     end
   end

activerecord/test/cases/dirty_test.rb

@@ -201,7 +201,7 @@ def test_nullable_float_not_marked_as_changed_if_new_value_is_blank
     end
   end
 
-  def test_nullable_integer_zero_to_string_zero_not_marked_as_changed
+  def test_integer_zero_to_string_zero_not_marked_as_changed
     pirate = Pirate.new
     pirate.parrot_id = 0
     pirate.catchphrase = 'arrr'
@@ -213,6 +213,19 @@ def test_nullable_integer_zero_to_string_zero_not_marked_as_changed
     assert !pirate.changed?
   end
 
+  def test_integer_zero_to_integer_zero_not_marked_as_changed
+    pirate = Pirate.new
+    pirate.parrot_id = 0
+    pirate.catchphrase = 'arrr'
+    assert pirate.save!
+
+    assert !pirate.changed?
+
+    pirate.parrot_id = 0
+    assert !pirate.changed?
+  end
+
+
   def test_zero_to_blank_marked_as_changed
     pirate = Pirate.new
     pirate.catchphrase = "Yarrrr, me hearties"