Merge branch 'fix-ruby-2-1-failures' into 'master'

Don't use Hash#slice since it's not supported in Ruby 2.1

There is currently a build failure in `master` and this MR fixes it. The issue was introduced by !6879.

The problem is that `Hash#slice` doesn't exists in Ruby 2.1. I've created an issue to take care of the other places we're using `Hash#slice`: #23590

See merge request !7025