From 6bc4418455856d2c9cab02d0d08c3e3647b2da5a Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Sat, 10 Jul 2021 00:00:50 +1000
Subject: [PATCH] Do not rearrange palette channels

---
 Tests/test_file_gif.py    |  2 +-
 src/PIL/GifImagePlugin.py | 10 +---------
 2 files changed, 2 insertions(+), 10 deletions(-)

diff --git a/Tests/test_file_gif.py b/Tests/test_file_gif.py
index 2632ab7c04f..05e2ddcbebb 100644
--- a/Tests/test_file_gif.py
+++ b/Tests/test_file_gif.py
@@ -833,7 +833,7 @@ def test_palette_save_ImagePalette(tmp_path):
 
     with Image.open(out) as reloaded:
         im.putpalette(palette)
-        assert_image_equal(reloaded, im)
+        assert_image_equal(reloaded.convert("RGB"), im.convert("RGB"))
 
 
 def test_save_I(tmp_path):
diff --git a/src/PIL/GifImagePlugin.py b/src/PIL/GifImagePlugin.py
index 5db31080958..a0e5618cb92 100644
--- a/src/PIL/GifImagePlugin.py
+++ b/src/PIL/GifImagePlugin.py
@@ -396,15 +396,7 @@ def _normalize_palette(im, palette, info):
         if isinstance(palette, (bytes, bytearray, list)):
             source_palette = bytearray(palette[:768])
         if isinstance(palette, ImagePalette.ImagePalette):
-            source_palette = bytearray(
-                itertools.chain.from_iterable(
-                    zip(
-                        palette.palette[:256],
-                        palette.palette[256:512],
-                        palette.palette[512:768],
-                    )
-                )
-            )
+            source_palette = bytearray(palette.palette)
 
     if im.mode == "P":
         if not source_palette: