Set locale for error messages.

git-svn-id: http://svn.redmine.org/redmine/trunk@13772 e93f8b46-1217-0410-a6f0-8f06a7374b81

test/unit/issue_test.rb

@@ -31,6 +31,10 @@ class IssueTest < ActiveSupport::TestCase
 
   include Redmine::I18n
 
+  def setup
+    set_language_if_valid 'en'
+  end
+
   def teardown
     User.current = nil
   end