thoughtbot/paperclip — pull request #1515 by quainjn (2014-04-11 16:11:47+00:00)
Title: Ensure required validations accepts subclasses

Allow users to create a custom validator that inherits from the acceptable paperclip validators, and will prevent an error from being raised in that case.

```
class MyValidator < Paperclip::Validators::AttachmentContentTypeValidator
end

validates_with MyValidator
```