fix inverse_of association in block of new child

This fixes inconsistency when building children of association
which has inverse_of set properly.

When creating new association object with a block:

    parent.association.build do |child|
      child.parent.equal?(parent) # false
    end

So the block the `child.parent` did not point to the same object.
But when the object is created it points to same instance:

    child = parent.association.build
    child.parent.equal?(parent) # true

1 files changed, 17 insertions, 0 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 0c8c8c006e..b4f14c3cc8 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -388,6 +388,23 @@
         # This will expand the order :name to "authors".name.
         Author.joins(:books).where('books.published = 1').order(:name)
 
+*   Fix associations with `:inverse_of` option when building association
+    with a block. Inside the block the parent object was different then
+    after the block.
+
+    Example:
+
+        parent.association.build do |child|
+          child.parent.equal?(parent) # false
+        end
+
+        # vs
+
+        child = parent.association.build
+        child.parent.equal?(parent) # true
+
+    *Michal Cichra*
+
 
 ## Rails 4.0.0.beta1 (February 25, 2013) ##