The image compress issue

[ReZeroS]

What did you do?

Reverse a gif get it much bigger size on disk

What did you expect to happen?

Still the original size or only a bit more

What versions of Pillow and Python are you using?

latest Pillow and 3.6 Python

from PIL import Image, ImageSequence
from PIL import ImagePalette
with Image.open('sd.gif') as im:
    if im.is_animated:
        frames = [f.copy() for f in ImageSequence.Iterator(im)]
        frames.reverse()
        frames[0].save('out.gif', save_all=True, append_images = frames[1:])  

[hugovk]

Duplicate of #617.