fix broken unit test (#2099)

Co-authored-by: peitili <62725319+peitili@users.noreply.github.com>

Author: tgrigsby-sc

test/test_transform.py

@@ -886,6 +886,10 @@ def test_best_overlap(self):
             if props['kind'] == 'building_part':
                 root_id = props.get('root_id')
                 self.assertEquals(root_id, 2)
+            elif props['kind'] == 'building':
+                root_id = props.get('root_id')
+                id = props.get('id')
+                self.assertEquals(root_id, id)
             else:
                 assert 'root_id' not in props