Add test to be able to create a PR

When branch only-allow-utc-timestamp-in-ids was merged into master,
a release tag wasn't assigned to it. Instead the release tag
was assigned to the previous release. So we ended up with a release
without a tag, and another release with two tags.

Hoping that redeploying the code in a new branch will resolve the
issue. Had to add a test because you can't create a PR on code that
is the same as master.

tests/core/test_data_set.py

@@ -244,6 +244,11 @@ def test_store_parses_timestamp_to_utc_before_generating_auto_id(self):
         self.mock_storage.save_record.assert_called_with(
             'test_data_set', match(has_entry('_id', expected_id)))
 
+        self.data_set.store([{"_timestamp": "2012-12-12T00:00:00"}])
+
+        self.mock_storage.save_record.assert_called_with(
+            'test_data_set', match(has_entry('_id', expected_id)))
+
 
 class TestDataSet_execute_query(BaseDataSetTest):