Fix that a collection proxy could be cached before the save of the owner, resulting in an invalid proxy lacking the owner’s id.

Absent this fix calls like: owner.association.update_all to behave unexpectedly because they try to act on association objects where
owner_id is null.

more evidence here: https://gist.github.com/Empact/5865555
```
Active Record 3.2.13
-- create_table(:firms, {:force=>true})
   -> 0.1371s
-- create_table(:clients, {:force=>true})
   -> 0.0005s
1 clients. 1 expected.
1 clients updated. 1 expected.
```

```
Active Record 4.0.0
-- create_table(:firms, {:force=>true})
   -> 0.1606s
-- create_table(:clients, {:force=>true})
   -> 0.0004s
1 clients. 1 expected.
0 clients updated. 1 expected.
```

1 files changed, 7 insertions, 0 deletions

diff --git a/activerecord/test/cases/associations/has_many_associations_test.rb b/activerecord/test/cases/associations/has_many_associations_test.rb
index e34b993029..c72d9342a9 100644
--- a/activerecord/test/cases/associations/has_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_many_associations_test.rb
@@ -387,6 +387,13 @@ class HasManyAssociationsTest < ActiveRecord::TestCase
     assert_equal "Summit", Firm.all.merge!(:order => "id").first.clients_using_primary_key.first.name
   end
 
+  def test_update_all_on_association_accessed_before_save
+    firm = Firm.new(name: 'Firm')
+    firm.clients << Client.first
+    firm.save!
+    assert_equal firm.clients.count, firm.clients.update_all(description: 'Great!')
+  end
+
   def test_belongs_to_sanity
     c = Client.new
     assert_nil c.firm, "belongs_to failed sanity check on new object"