only process thumbnails if process_attachment_with_processing is defined

git-svn-id: http://svn.techno-weenie.net/projects/plugins/attachment_fu@2603 567b1171-46fb-0310-a4c9-b4bef9110e78

lib/technoweenie/attachment_fu.rb

@@ -343,7 +343,7 @@ module Technoweenie # :nodoc:
         # Cleans up after processing.  Thumbnails are created, the attachment is stored to the backend, and the temp_paths are cleared.
         def after_process_attachment
           if @saved_attachment
-            if thumbnailable? && !attachment_options[:thumbnails].blank? && parent_id.nil?
+            if respond_to?(:process_attachment_with_processing) && thumbnailable? && !attachment_options[:thumbnails].blank? && parent_id.nil?
               temp_file = temp_path || create_temp_file
               attachment_options[:thumbnails].each { |suffix, size| create_or_update_thumbnail(temp_file, suffix, *size) }
             end