Separate multiple GIF comment blocks with newlines

Tests/test_file_gif.py

@@ -813,6 +813,12 @@ def test_zero_comment_subblocks():
         assert_image_equal_tofile(im, TEST_GIF)
 
 
+def test_read_multiple_comment_blocks():
+    with Image.open("Tests/images/multiple_comments.gif") as im:
+        # Multiple comment blocks in a frame are separated not concatenated
+        assert im.info["comment"] == b"Test comment 1\nTest comment 2"
+
+
 def test_version(tmp_path):
     out = str(tmp_path / "temp.gif")
 

src/PIL/GifImagePlugin.py

@@ -228,12 +228,18 @@ def _seek(self, frame, update_image=True):
                     #
                     # comment extension
                     #
+                    comment = b""
+
+                    # Collect one comment block
                     while block:
-                        if "comment" in info:
-                            info["comment"] += block
-                        else:
-                            info["comment"] = block
+                        comment += block
                         block = self.data()
+
+                    if "comment" in info:
+                        # If multiple comment blocks in frame, separate with \n
+                        info["comment"] += b"\n" + comment
+                    else:
+                        info["comment"] = comment
                     s = None
                     continue
                 elif s[0] == 255: