Merge pull request #2218 from guilleiguaran/avoid-map-chaining

Remove unneccesary map chaining

activesupport/lib/active_support/ordered_hash.rb

@@ -6,7 +6,7 @@
 require 'yaml'
 
 YAML.add_builtin_type("omap") do |type, val|
-  ActiveSupport::OrderedHash[val.map(&:to_a).map(&:first)]
+  ActiveSupport::OrderedHash[val.map{ |v| v.to_a.first }]
 end
 
 module ActiveSupport