http://twitter.com/#!/necocen/status/182161794570260481 これをなんとかするコード(インデントはスペース二個、タブの場合はいくらか変更が必要)。RAILS_ROOT/config/initializersに置くと動く。

fix_form_tag_helper.rb

module ActionView::Helpers::FormTagHelper
  def extra_tags_for_form(html_options)
    authenticity_token = html_options.delete("authenticity_token")
    method = html_options.delete("method").to_s

    method_tag = case method
                 when /^get$/
                   html_options["method"] = "get"
                   ''
                 when /^post$/, "", nil
                   html_options["method"] = "post"
                   ((authenticity_token == false || !protect_against_forgery?) ? "" : "\n    ") << token_tag(authenticity_token)
                 else
                   html_options["method"] = "post"
                   "\n    " << tag(:input, :type => "hidden", :name => "_method", :value => method)
                 end
    tags = "\n    " << utf8_enforcer_tag << method_tag << "\n  "
    "  " << content_tag(:div, tags, {:style => 'margin:0;padding:0;display:inline;'}, false)
  end

  def form_tag_html(html_options)
    extra_tags = extra_tags_for_form(html_options).html_safe
    (tag(:form, html_options, true) + "\n" + extra_tags).html_safe
  end
end