Upgrading from Ractive.js v0.5.8 to v0.7.1 and making a call to file Ractive.js.map

I am upgrading an application from Ractive JS v0.5.8 to v0.7.1 and in the browser console, I am getting a 403 (Forbidden) request calling:

http://ift.tt/1EQeTJ4 

What is causing this request, and how do I remedy it?