function setupRepo(fixtureName, options) {
  const branch = options.branch || 'gh-pages';
  const userEmail = (options.user && options.user.email) || 'user@email.com';
  const userName = (options.user && options.user.name) || 'User Name';
  return mkdtemp()
    .then((dir) => {
      const fixturePath = path.join(fixtures, fixtureName, 'remote');
      return fs.copy(fixturePath, dir).then(() => new Git(dir));
    })
    .then((git) => git.init())
    .then((git) => git.exec('config', 'user.email', userEmail))
    .then((git) => git.exec('config', 'user.name', userName))
    .then((git) => git.exec('checkout', '--orphan', branch))
    .then((git) => git.add('.'))
    .then((git) => git.commit('Initial commit'))
    .then((git) => git.cwd);
}
Creates a git repo with the contents of a fixture.
@param {string} fixtureName Name of fixture.
@param {Object} options Repo options.
@return {Promise<string>} A promise for the path to the repo.