Invalid Tiff Prefix (Possible Corrupted Image), is there a good way to fix this ?

Hi,
I have a portal running since 2011. This year we upgraded from PIL to Pillow. 

This upgrade broke our thumbnail generation for some Tiffs. The prefix validation was breaking our script.

After debugging I found that our prefix are different, I added those prefix to my fork. But I think the image is corrupted.

Is that correct ? Check the prefix values.

By the way, I will need this "hack". Is there a better place to handle this ? Please give me a hint.

ps: I created a PR  instead of a Issue to show diffs easily.

Thanks,
Paulo.