From fcaf27d51cfb9f92eb46a1194ae4ad75d1d65d5b Mon Sep 17 00:00:00 2001
From: djy0 <krivergo3@gmail.com>
Date: Fri, 2 Aug 2019 08:54:04 +0800
Subject: [PATCH] Update GifImagePlugin.py

---
 src/PIL/GifImagePlugin.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/src/PIL/GifImagePlugin.py b/src/PIL/GifImagePlugin.py
index bbf6dc9d6..b5323d252 100644
--- a/src/PIL/GifImagePlugin.py
+++ b/src/PIL/GifImagePlugin.py
@@ -472,6 +472,10 @@ def _write_multiple_frames(im, fp, palette):
             else:
                 bbox = None
             im_frames.append({"im": im_frame, "bbox": bbox, "encoderinfo": encoderinfo})
+    
+    # see: https://github.com/python-pillow/Pillow/issues/4002
+    if len(im_frames) == 1 and 'duration' in im_frames[0]['encoderinfo']:
+        im.encoderinfo['duration'] = im_frames[0]['encoderinfo']['duration']
 
     if len(im_frames) > 1:
         for frame_data in im_frames: