From 8d73c252be365868c8d7b98015ea968ead167da4 Mon Sep 17 00:00:00 2001
From: Lars Ingebrigtsen <larsi@gnus.org>
Date: Wed, 24 Aug 2016 00:31:57 +0200
Subject: [PATCH] Fix invalid image rotations

* lisp/image.el (image-rotate): Limit rotation to 360 degrees.
---
 lisp/image.el | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/lisp/image.el b/lisp/image.el
index 08df7d4aa1a..272cee53e4f 100644
--- a/lisp/image.el
+++ b/lisp/image.el
@@ -1013,7 +1013,11 @@ default is 20%."
   (interactive)
   (let ((image (image--get-imagemagick-and-warn)))
     (plist-put (cdr image) :rotation
-               (float (+ (or (plist-get (cdr image) :rotation) 0) 90)))))
+               (float (mod (+ (or (plist-get (cdr image) :rotation) 0) 90)
+                           ;; We don't want to exceed 360 degrees
+                           ;; rotation, because it's not seen as valid
+                           ;; in exif data.
+                           360)))))
 
 (defun image-save ()
   "Save the image under point."
-- 
2.39.2