Don't require test/unit since it tries to turn everything into a test run.

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@5740 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

activesupport/lib/active_support/deprecation.rb

@@ -172,7 +172,7 @@ class Module
   include ActiveSupport::Deprecation::ClassMethods
 end
 
-require 'test/unit'
+require 'test/unit/error'
 
 module Test
   module Unit