merges don't work in syck on ruby 2.2 with strict safety

[ccutrer]

ruby 2.2.3, syck 1.0.4

require 'yaml'
require 'syck'
require 'safe_yaml'

yaml = <<-YAML
common: &common
  adapter: postgresql

development:
 <<: *common
YAML

SafeYAML::OPTIONS[:default_mode] = :safe

YAML.load(yaml) # => {"common"=>{"adapter"=>"postgresql"}, "development"=>{"adapter"=>"postgresql"}}, as expected

SafeYAML::OPTIONS[:raise_on_unknown_tag] = true
YAML.load(yaml) # RuntimeError: Unknown YAML tag 'tag:yaml.org,2002:merge'

[ccutrer]

Oh, and to continue:

SafeYAML::OPTIONS[:whitelisted_tags] = ['tag:yaml.org,2002:merge']
YAML.load(yaml) # => {"common"=>{"adapter"=>"postgresql"}, "development"=>{#<Syck::MergeKey:0x007f89aaa379c0>=>{"adapter"=>"postgresql"}}}