Prefill translation form with old translation if possible

test/controllers/translations_controller_test.rb

@@ -23,11 +23,16 @@ class TranslationsControllerTest < ActionController::TestCase
     assert_not_nil assigns(:translations)
   end
 
-  test "should get new" do
+  test "should get new for translated problem" do
     get :new, problem_id: 1
     assert_response :success
   end
 
+  test "should get new for untranslated problem" do
+    get :new, problem_id: 3
+    assert_response :success
+  end
+
   test "should create translation" do
     assert_difference('Translation.count') do
       post :create, problem_id: 1, translation: @update