rails/rails — pull request #5156 by avakhov (2012-02-24 21:36:11+00:00)
Title: Add instance_accessor option to class_attribute

option for cattr_accessor was added at Jun 2011 - b12c2e4ebb85170467ac250219557d631c842d8d,
for mattr_accessor at the same time: bf526c2dbeb73bf11553004e43889a804b72866d

I suggest to add this option to class_attribute also.