test: mark expectedFailure current known problems

Some tests for current known problems have been added in 0fdd241a (Add a
test to check whether update of a part of repeated elements works.,
2015-08-25) and ac8d33af (Add test to check whether insert-{before,after}
with same ids is working fine., 2011-12-16), but they never seem to have
passed. Mark them as expected failures for now.

src/tests/erp5diff_test_suite.py

@@ -1112,6 +1112,7 @@ class TestERP5Diff(unittest.TestCase):
 """
     self._assertERP5DiffWorks(old_xml, new_xml, expected_result_string)
 
+  @unittest.expectedFailure
   def test_insert_element_with_same_id(self):
     """31. Insert elements with the same ids with the proper
     indexes
@@ -1185,6 +1186,7 @@ class TestERP5Diff(unittest.TestCase):
 """
     self._assertERP5DiffWorks(old_xml, new_xml, expected_result_string)
 
+  @unittest.expectedFailure
   def test_part_of_repeated_elements_updated(self):
     """32. Update a part of repeated elements
     """