Link tasks to their restarts

Closes #1711 (closed)

arkindex/ponos/tests/test_api.py

@@ -635,6 +635,7 @@ class TestAPI(FixtureAPITestCase):
             mock_now.return_value = datetime.now(timezone.utc) + timedelta(minutes=1)
             old_task_2 = self.process.tasks.create(run=self.task1.run, depth=1, slug=f"{task_2_slug}_old1")
             old_task_2.state = State.Error.value
+            old_task_2.original_task_id = self.task1.id
             old_task_2.save()
         old_task_2.parents.add(self.task1)
         self.task1.state = State.Completed.value