Incorrect decoding of some rare GIFs

[Shnatsel]

I scraped 10,000 GIF files from https://gifcities.org/ and found two that decode incorrectly: incorrectly_decoded_gifs.zip

Expected decoding of the first frame:

Actual decoding of the first frame:

One color becomes transparent where it shouldn't.

Tested on gif crate v0.13.1 from crates.io

[197g]

...

[197g]

I don't think I can reproduce this on the current head commit. Here's running the output of running the explode example:

It was (by bisect) fixed in ed26c15 although I can not tell why.

[Shnatsel]

Yup, it was never shipped. And the latest git is not shippable because #202 is a breaking change.

Should we temporarily undo that PR and ship the fixes in a semver-compatible release?

[fintelia]

Another option is to checkout e2990d5, the commit that was meant to be released, and publish that as 0.13.2

[Shnatsel]

We also want to include #210 which is also a fix relevant to Glycin. So we need to either backport that to 0.13.x or make ships a semver-compatible release of image that wraps gif 0.14.x so that Glycin could get the fix when it ships in GNOME 49 on the 17th of September.

[197g]

I can do the backport over the weekend. @fintelia can you ship 0.13.2 at e2990d5 where it was originally intended? I'll then branch a backport from there and integrate the fixes of #210 for a 0.13.3 separately, as a one-off decision since gif did not have a major bump for long and 0.14 will likely only make it into the next major version of image, too.