indifferent access should recurse Hash subclasses

This commit makes Hash subclasses convert to HWIA by default for nested
objects of subclasses of Hash, but allows certain subclasses to prevent nested
conversion by introducing Hash#nested_under_indifferent_access that subclasses
can overwrite.

ActiveSupport::OrderedHash is one such subclass that overwrites
+nested_under_indifferent_access+, since implicitly converting it to HWIA would
remove the ordering of keys and values in Ruby 1.8.

This change is necessary because commit ce9456e broke nested indifferent access
conversion for all subclasses of Hash.

1 files changed, 2 insertions, 2 deletions

diff --git a/activesupport/lib/active_support/hash_with_indifferent_access.rb b/activesupport/lib/active_support/hash_with_indifferent_access.rb
index 79a0de7940..8ec4f6e09a 100644
--- a/activesupport/lib/active_support/hash_with_indifferent_access.rb
+++ b/activesupport/lib/active_support/hash_with_indifferent_access.rb
@@ -140,8 +140,8 @@ module ActiveSupport
       end
 
       def convert_value(value)
-        if value.class == Hash
-          self.class.new_from_hash_copying_default(value)
+        if value.is_a? Hash
+          value.nested_under_indifferent_access
         elsif value.is_a?(Array)
           value.dup.replace(value.map { |e| convert_value(e) })
         else