Saving to apng has wrong durations about pillow

[radarhere]

Regarding saving to APNG, I've created #8104

I'm having trouble convincing ImageMagick to tell me the durations on my local machine or on GitHub Actions. I opened different_durations.png with https://davidmz.github.io/apng-js/ and it reported 4000 and 1000. If you think that ImageMagick isn't reading the duration according to the specification, then maybe that's something for you to raise with ImageMagick?

[Yay295]

I don't know why I didn't check this before, but saving from APNG to APNG has the same issue; it not only when the source is a GIF.

from PIL import Image, ImageSequence
ddp = Image.open('different_durations.png')
ddp.save('ddc.png',save_all=True)
ddc = Image.open('ddc.png')
print([frame.info.get('duration') for frame in ImageSequence.Iterator(ddc)]) # [1000.0, 1000.0]

I think it probably is an issue in ImageMagick, or perhaps in libpng. I've filed an issue with ImageMagick though.

[radarhere]

The ImageMagick issue is ImageMagick/ImageMagick#7371

[radarhere]

ImageMagick has made a change to fix their problem.