PIL.ImageOps.exif_transpose() fails on some PNGs

[doublex]

Testcase (extension should be .py):
testcase.txt

Pillow 8.1 works, 8.2 fails

Traceback:

  File "/home/max/.local/lib/python3.8/site-packages/PIL/PngImagePlugin.py", line 940, in load_end
    self.png.call(cid, pos, length)
  File "/home/max/.local/lib/python3.8/site-packages/PIL/PngImagePlugin.py", line 187, in call
    return getattr(self, "chunk_" + cid.decode("ascii"))(pos, length)
AttributeError: 'PngStream' object has no attribute 'chunk_'

[radarhere]

Just to clarify, the issue doesn't relate to exif_transpose(). It's our generic load() method. Testing, the error started after 22e9bee. So this may not be a bug as much as a security measure.

You probably know, but if you don't enable LOAD_TRUNCATED_IMAGES, then the error doesn't appear.

[radarhere]

Actually, I've found that this would be fixed by #5493, making this a duplicate of #5491.

[radarhere]

#5493 has been merged, so this should be fixed in the next version of Pillow. due out on July 1.

[doublex]

@radarhere
Thank you so much for pillow!