Subject: 25.1.50; org-timestamp-change: Invalid time zone specification: (nil nil nil)

From: Paul Eggert <[email-masked]>
Date: Wed, 20 Apr 2016 00:11:15 -0700

Thanks for reporting the problem. As Eli suggested, it was a typo in org.el that 
was exposed by recent changes to encode-time. I installed into master the 
attached patch, which I think fixes the bug.
From 313ebbbb98ceb078468498998305749b2790b7ba Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email-masked]>
Date: Wed, 20 Apr 2016 00:06:01 -0700
Subject: [PATCH] Fix org-timestamp-change typo
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Problem reported by Peter Münster (Bug#23299).
* lisp/org/org.el (org-timestamp-change): Fix typo that relied
on undocumented behavior in ‘encode-time’.  In practice the
old code used local time, so use that.
---
 lisp/org/org.el | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/lisp/org/org.el b/lisp/org/org.el
index 3abf627..b0e1e20 100644
--- a/lisp/org/org.el
+++ b/lisp/org/org.el
@@ -17459,8 +17459,7 @@ org-timestamp-change
 			 (+ (if (eq org-ts-what 'hour) n 0)   (nth 2 time0))
 			 (+ (if (eq org-ts-what 'day) n 0)    (nth 3 time0))
 			 (+ (if (eq org-ts-what 'month) n 0)  (nth 4 time0))
-			 (+ (if (eq org-ts-what 'year) n 0)   (nth 5 time0))
-			 (nthcdr 6 time0)))
+			 (+ (if (eq org-ts-what 'year) n 0)   (nth 5 time0))))
       (when (and (member org-ts-what '(hour minute))
 		 extra
 		 (string-match "-\\([012][0-9]\\):\\([0-5][0-9]\\)" extra))
-- 
2.5.5