rails/rails — pull request #18177 by hsbt (2014-12-24 01:07:23+00:00)
Title: added dependency of test-unit into activesupport

this pull request is related with https://github.com/rails/rails/pull/18160

test-unit will be removed from standard library of Ruby 2.2. I understood to fix only security issue on 3-2-stable branch.

/cc @tmm1