[Rails-core] Rails 5.0.5.rc2 and 5.1.3.rc2 released

Hi everyone, I am happy to announce that Rails 5.0.5.rc2 and 5.1.3.rc2 have been released. If no regressions are found, expect the final release on Monday, July 31, 2017. If you find one, please open an [issue on GitHub](https://github.com/rails/rails/issues/new) and mention me (@github_user})

Re: [Rails-core] Break out testing library from ActiveSupport?

I just found this thread after noticing the same dependency today and looking for a way to potentially remove this. I don't quite see a dependency on minitest in the 'standard library' (by which I assume you mean the Rails gem itself). https://github.com/rails/rails/blob/master/rails.gemspec