fphilipe/premailer-rails3 — pull request #22 by martincik (2012-02-27 23:07:18+00:00)
Title: Nokogiri::XML::Attr and calling sub Ruby 1.9.3-p125

As for me this can be Nokogiri::XML::Attr and we need to call explicitly to_s to be able to use sub method. Tested on 1.9.3-p125