From a06191238f889c517de6c63b8517f85f29d79f4d Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 22 Sep 2025 12:10:50 -0700
Subject: [PROPOSED 2/2] Add commentary on UTC/-00 patch

---
 NEWS        | 6 ++++++
 localtime.c | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/NEWS b/NEWS
index 4b5fac51..0ad9b891 100644
--- a/NEWS
+++ b/NEWS
@@ -22,6 +22,12 @@ Unreleased, experimental changes
     MANFLAGS can override these defaults.  (Thanks to G. Branden
     Robinson for inspiring these changes.)
 
+  Changes to code
+
+    An unset TZ is no longer invalid when /etc/localtime is missing,
+    and is abbreviated "UTC" not "-00".  This reverts to 2024b behavior.
+    (Problem and patch reported by Dag-Erling Smørgrav.)
+
   Changes to commentary
 
     The leapseconds file contains commentary about the IERS and NIST
diff --git a/localtime.c b/localtime.c
index 1c6c1a46..1226e6e0 100644
--- a/localtime.c
+++ b/localtime.c
@@ -1487,6 +1487,8 @@ tzset_unlocked(void)
     int err = zoneinit(sp, name, TZLOAD_FROMENV | TZLOAD_TZSTRING);
     if (err != 0) {
       zoneinit(sp, "", 0);
+      /* Abbreviate with "-00" if there was an error.
+	 Do not treat a missing TZDEFAULT file as an error.  */
       if (name || err != ENOENT)
 	strcpy(sp->chars, UNSPEC);
     }
-- 
2.48.1