https://github.com/WayneD/rsync/issues/427
https://github.com/WayneD/rsync/issues/429
https://github.com/WayneD/rsync/commit/90df93e446f9ebbfd4ce97d6755c5fe1f45f9fd0

From 90df93e446f9ebbfd4ce97d6755c5fe1f45f9fd0 Mon Sep 17 00:00:00 2001
From: Wayne Davison <wayne@opencoder.net>
Date: Sun, 8 Jan 2023 21:35:39 -0800
Subject: [PATCH] Don't call memcmp() on an empty lastdir.

--- a/flist.c
+++ b/flist.c
@@ -2367,7 +2367,7 @@ struct file_list *send_file_list(int f, int argc, char *argv[])
 		}
 
 		dirlen = dir ? strlen(dir) : 0;
-		if (dirlen != lastdir_len || memcmp(lastdir, dir, dirlen) != 0) {
+		if (dirlen != lastdir_len || (dirlen && memcmp(lastdir, dir, dirlen) != 0)) {
 			if (!change_pathname(NULL, dir, -dirlen))
 				goto bad_path;
 			lastdir = pathname;