Faraday's multipart support and ruby-filemagic

[amw]

Hi, I've ran into a problem when using faraday (through zendesk client gem) and ruby-filemagic gems at the same time.

Ruby-filemagic defines content_type on String and faraday checks for that method to detect files. More info in an issue at zendesk client:
zendesk/zendesk_api_client_rb#61

I would create an issue at ruby-filemagic since content_type is a little unexpected on a String, but I think it's actually faraday that doesn't adhere to the "quacks like a duck" rule. It's ok to check for respond_to? instead of kind_of?, but you should check all the methods you intend to use. Faraday uses but doesn't verify existence of original_filename method.

[amw]

It seems it's actually an issue in multipart-post:
socketry/multipart-post#20