# HG changeset patch
# User pacien <pacien.trangirard@pacien.net>
# Date 2023-05-22 17:04:05
# Node ID 4fd2f7ab4177f0b3dedc99319fe090ab8f2883c3
# Parent  1a4f54574e3d63fdd5d6ad6285245e6b281d76b5

stabletailgraph: clarify excl part size computation

diff --git a/mercurial/stabletailgraph/stabletailsort.py b/mercurial/stabletailgraph/stabletailsort.py
--- a/mercurial/stabletailgraph/stabletailsort.py
+++ b/mercurial/stabletailgraph/stabletailsort.py
@@ -108,6 +108,9 @@ def _stable_tail_sort_naive(cl, head_rev
                 if a not in tail_ancestors
             )
 
+            # Notice that excl(cur) is disjoint from ancestors(pt),
+            # so there is no double-counting:
+            # rank(cur) = len([cur]) + len(excl(cur)) + rank(pt)
             excl_part_size = cl.fast_rank(cursor_rev) - cl.fast_rank(pt) - 1
             yield from itertools.islice(exclusive_ancestors, excl_part_size)
             cursor_rev = pt