Do not save instances unless they have already been persisted. This allows AR's…

Do not save instances unless they have already been persisted. This allows AR's behaviour for unsaved instances to be preserved.

lib/paranoia.rb

@@ -10,8 +10,10 @@ module Paranoia
   def destroy
     _run_destroy_callbacks
     self[:deleted_at] ||= Time.now
-    self.save(:validate => false)
-    self.freeze
+    # If the instance has already been persisted, then we need to re-save it to flag it as
+    # destroyed / deleted.  We don't require validation in case it causes the updated to fail.
+    save(:validate => false) if persisted?
+    freeze
   end
   alias :delete :destroy