Testem appends random number to url -- breaks my app!

[Al J]

I'm trying to use Testem to test my webapp and it's appending a random number to the url everytime it opens a browser

    testem: {

      environment1: {

        options: {

          url: 'http://localhost:9000/',

          launch_in_ci: ['Chrome']

        }

      }

    },

Running this config (which is supposed to just open the webpage at this point) three times will result in three different urls 

(the appended numbers are never the same)

     http://localhost:9000/4680

     http://localhost:9000/841

     http://localhost:9000/3796

What is going on here?