buster.js failing stubs since sinon 1.7 release

buster.js

var config = module.exports;

config.Tests = {
    env: 'browser',
    tests: [
        '*Spec.js'
    ]
};

package.json

{
  "name": "foo",
  "version": "0.0.0",
  "description": "ERROR: No README.md file found!",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": "",
  "author": "",
  "license": "BSD",
  "dependencies": {
      "buster": "0.6.x"
  }
}

StubSpec.js

buster.spec.expose();

describe('stubbing', function () {
  it('should stub', function () {
    var stub = this.stub().returns(1);
    expect(stub()).toBe(1);
  });
});