Merged r10137 from trunk to 2.0-stable (#10320, #10818)

Gemfile: prevent "rake db:migrate RAILS_ENV=test" causes exception on Ruby 1.9.3.

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/branches/2.0-stable@10138 e93f8b46-1217-0410-a6f0-8f06a7374b81

Gemfile

@@ -74,6 +74,8 @@ end
 
 group :test do
   gem "shoulda", "~> 2.11"
+  # Shoulda does not work nice on Ruby 1.9.3 and seems to need test-unit explicitely.
+  gem "test-unit", :platforms => [:mri_19]
   gem "mocha"
 end