Add a clarifying comment

sparse_strips/vello_common/src/coarse.rs

diff --git a/sparse_strips/vello_common/src/coarse.rs b/sparse_strips/vello_common/src/coarse.rs
index 79ca1be..cbbc58f 100644
--- a/sparse_strips/vello_common/src/coarse.rs
+++ b/sparse_strips/vello_common/src/coarse.rs
@@ -475,7 +475,9 @@
                 cur_wtile_y += 1;
             }
 
-            // If we've reached the bottom of the clip bounding box, stop processing
+            // If we've reached the bottom of the clip bounding box, stop processing.
+            // Note that we are explicitly checking >= instead of ==, so that we abort if the clipping box
+            // is zero-area (see issue 1072).
             if cur_wtile_y >= clip_bbox.y1() {
                 break;
             }
@@ -597,6 +599,8 @@
             }
 
             // If we've reached the bottom of the clip bounding box, stop processing
+            // Note that we are explicitly checking >= instead of ==, so that we abort if the clipping box
+            // is zero-area (see issue 1072).
             if cur_wtile_y >= clip_bbox.y1() {
                 break;
             }