Merge pull request #6292 from raygard/comment_use_gif89a

Always use GIF89a for comments

Tests/test_file_gif.py

@@ -807,6 +807,9 @@ def test_comment(tmp_path):
     with Image.open(out) as reread:
         assert reread.info["comment"] == im.info["comment"].encode()
 
+        # Test that GIF89a is used for comments
+        assert reread.info["version"] == b"GIF89a"
+
 
 def test_comment_over_255(tmp_path):
     out = str(tmp_path / "temp.gif")
@@ -817,9 +820,11 @@ def test_comment_over_255(tmp_path):
     im.info["comment"] = comment
     im.save(out)
     with Image.open(out) as reread:
-
         assert reread.info["comment"] == comment
 
+        # Test that GIF89a is used for comments
+        assert reread.info["version"] == b"GIF89a"
+
 
 def test_zero_comment_subblocks():
     with Image.open("Tests/images/hopper_zero_comment_subblocks.gif") as im:

src/PIL/GifImagePlugin.py

@@ -903,17 +903,16 @@ def _get_global_header(im, info):
     # https://www.matthewflickinger.com/lab/whatsinagif/bits_and_bytes.asp
 
     version = b"87a"
-    for extensionKey in ["transparency", "duration", "loop", "comment"]:
-        if info and extensionKey in info:
-            if (extensionKey == "duration" and info[extensionKey] == 0) or (
-                extensionKey == "comment" and not (1 <= len(info[extensionKey]) <= 255)
-            ):
-                continue
-            version = b"89a"
-            break
-    else:
-        if im.info.get("version") == b"89a":
-            version = b"89a"
+    if im.info.get("version") == b"89a" or (
+        info
+        and (
+            "transparency" in info
+            or "loop" in info
+            or info.get("duration")
+            or info.get("comment")
+        )
+    ):
+        version = b"89a"
 
     background = _get_background(im, info.get("background"))