Refactor previous commit.

lib/paperclip/interpolations.rb

@@ -35,7 +35,7 @@ module Paperclip
 
     # Returns the filename, the same way as ":basename.:extension" would.
     def filename attachment, style_name
-      (ext = extension(attachment, style_name)).blank? ? basename(attachment, style_name) : "#{basename(attachment, style_name)}.#{ext}"
+      [ basename(attachment, style_name), extension(attachment, style_name) ].reject(&:blank?).join(".")
     end
 
     # Returns the interpolated URL. Will raise an error if the url itself