记录一个错误，在bundle install时候出现 shoulda-mathcers bundle install fails with git error

复制粘体错误到google。找到解决方案：

https://github.com/thoughtbot/shoulda-matchers/issues/1057

GIT
  remote: https://github.com/thoughtbot/shoulda-matchers.git
  revision: f800d62525a65f9bf001ea984ae4926a92ff5b82
  branch: rails-5   #改为master,因为官方把分支合并了。