Fixes custom_field_tag helper broken by r9682.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@9686 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/helpers/custom_fields_helper.rb

@@ -51,7 +51,7 @@ module CustomFieldsHelper
     when "bool"
       hidden_field_tag(field_name, '0') + check_box_tag(field_name, '1', custom_value.true?, tag_options)
     when "list"
-      blank_option = ''
+      blank_option = ''.html_safe
       unless custom_field.multiple?
         if custom_field.is_required?
           unless custom_field.default_value.present?