Slightly less annoying check for acceptable mime_types. This allows Accept: application/json, application/jsonp (and the like), but still blacklists browsers. Essentially, we use normal content negotiation unless you include */* in your list, in which case we assume you're a browser and send HTML [#3541 state:resolved]

actionpack/lib/action_dispatch/http/mime_negotiation.rb

@@ -48,7 +48,7 @@ module ActionDispatch
         @env["action_dispatch.request.formats"] ||=
           if parameters[:format]
             Array(Mime[parameters[:format]])
-          elsif xhr? || (accept && !accept.include?(?,))
+          elsif xhr? || (accept && accept !~ /,\s*\*\/\*/)
             accepts
           else
             [Mime::HTML]
@@ -87,4 +87,4 @@ module ActionDispatch
       end
     end
   end
-end
+end