Handle missing InRelease files

[wraithm]

An InRelease file is just a Release file that's signed inline. If a repo has a Release and Release.gpg file, you can just ignore the InRelease file.

I've found that apt-s3 fails when the InRelease file is missing. We're mirroring the apt.vector.dev repo (from https://github.com/vectordotdev/vector). This repository only includes a Release and Release.gpg file, which is usually acceptable.

Using the normal https method, this repo works just fine, the InRelease file simply gets skipped over.

Here's the error message from apt update:

E: Method s3 has died unexpectedly!
E: Sub-process s3 returned an error code (1)

I was able to deduce that apt-s3 is calling os.Exit(1) when a requested file isn't found in the bucket. However, in this particular case, it's okay for InRelease to be missing.

I found that I was able to make this repo work by signing the Release file with my own key to make an InRelease file in the S3 bucket.