doc: replace more gmane links

Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/tree-walk.c b/tree-walk.c
index ff77605..f25a08f 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -1075,7 +1075,7 @@ static enum interesting do_match(const struct name_entry *entry,
 		 * later on.
 		 * max_depth is ignored but we may consider support it
 		 * in future, see
-		 * http://thread.gmane.org/gmane.comp.version-control.git/163757/focus=163840
+		 * https://public-inbox.org/git/7vmxo5l2g4.fsf@alter.siamese.dyndns.org/
 		 */
 		if (ps->recursive && S_ISDIR(entry->mode))
 			return entry_interesting;