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 <egg...@penguin.cs.ucla.edu>
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
