Got this answer from Mailchimp about maintaining this repository, does not look good:
Thank you for writing in to MailChimp support, I'm Jon with Mandrill. I apologize for the delay in getting back to you. Our integration pages have not been actively maintained by our developers for some time now, and likely will not for the foreseeable future. In all honesty, I wouldn't count on those pull requests being accepted any time soon, so if there are issues that are preventing you from moving forward, you may want to look into other ways of utilizing Mandrill in your application. If you have any other questions, please let us know.