Don't test Rails 4.x against MRI 2.4.
Don't test Rails 4.x against MRI 2.4.

Rails 4.1 and 4.2 require the json gem at a version that won't compile in MRI 2.4. So, only Rails 5 is going to be run against 2.4 for the moment.

pat/thinking-sphinx,pat/thinking-sphinx