tests taking a long time to start

[symbyte]

When I follow the advice in the readme to help my tests run faster by using a pattern object for my 3rd party libraries like this:

systemjs: {
  serveFiles: [
    {pattern: 'node_modules/**/*.js, watched: false}
  [
}

I get the following warning and none of my dependencies are loaded:
27 07 2016 13:07:34.986:WARN [watcher]: Pattern "node_modules/**/*.js" does not match any file.

though if I use the same pattern like so:

systemjs: {
  serveFiles: [
    'node_modules/**/*.js
  [
}

everything loads as you would expect (but the tests run extremely slow).

karma-systemjs version: 0.13.0
karma version: 0.13.22