Better handling of attachments when issue validation fails (#10253).

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@8891 e93f8b46-1217-0410-a6f0-8f06a7374b81

test/unit/attachment_test.rb

@@ -38,6 +38,10 @@ class AttachmentTest < ActiveSupport::TestCase
     set_tmp_attachments_directory
   end
 
+  def test_container_for_new_attachment_should_be_nil
+    assert_nil Attachment.new.container
+  end
+
   def test_create
     a = Attachment.new(:container => Issue.find(1),
                        :file => uploaded_test_file("testfile.txt", "text/plain"),