Add additional context to testing non sequential ids

tests/matchers/test_iou.py

@@ -135,7 +135,11 @@ def test_input_error(self):
         "data", [ex_segs.no_overlap_2d(), ex_segs.no_overlap_3d()], ids=["2D", "3D"]
     )
     def test_non_sequential(self, data):
-        # test when the segmentation ids are high numbers (the lower numbers should never appear)
+        """test when the segmentation ids are high numbers (the lower numbers should never appear)
+        At one point dummy nodes introduced from padding the iou matrix were appearing in the final
+        matching
+        See https://github.com/Janelia-Trackathon-2023/traccuracy/pull/173#discussion_r1882231345
+        """
         gt, pred = data[0], data[1]
         # Change id of segmentation to non sequntial high value
         gt[gt == 1] = 100