Fix touching an invalid parent record for belongs_to

If the parent of a `belongs_to` record fails to be saved due to
validation errors, `touch` will be called on a new record, which causes
an exception (see https://github.com/rails/rails/pull/9320).

Example:

    class Owner < ActiveRecord::Base
      validates_presence_of :name
    end

    class Pet < ActiveRecord::Base
      belongs_to :owner, touch: true
    end

    pet = Pet.new(owner: Owner.new)

    # Before, this line would raise ActiveRecord::ActiveRecordError
    # "can not touch on a new record object"
    pet.save

1 files changed, 6 insertions, 1 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 982fbdc236..44f3115add 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,5 +1,10 @@
 ## Rails 4.0.0 (unreleased) ##
 
+*   Do not try to touch invalid (and thus not persisted) parent record
+    for a `belongs_to :parent, touch: true` association
+
+    *Olek Janiszewski*
+
 *   Fix when performing an ordered join query. The bug only
     affected queries where the order was given with a symbol.
     Fixes #9275.
@@ -12,7 +17,7 @@
 
 ## Rails 4.0.0.beta1 (February 25, 2013) ##
 
-*   Fix overriding of attributes by default_scope on `ActiveRecord::Base#dup`.
+*   Fix overriding of attributes by `default_scope` on `ActiveRecord::Base#dup`.
 
     *Hiroshige UMINO*