Fix reading with limit and global-revisions

[felixjung]

I think I introduced a bug with #158. This should address it.

When processing the earliest commit of the commit history, no file content
outside the history is present. This means that no changes can be calculated
for the earliest commit.

This issue was likely always present but surfaced by the introduction of the --global-revisions flag. Previously, the issue would only appear when reaching the commit that introduced a file or the end of the repository's history.

To address the problem, we now read the file's content at the previous commit in the repo. The code fails gracefully, if git returns an error when attempting to read the file.

[felixjung]

This works for me locally, but it somehow fails in GitHub actions. Going to debug before asking to merge this.

Error: unable to read git repository './' (are you sure it's a git repo?): exit status 128

[daveshanley]

This works for me locally, but it somehow fails in GitHub actions. Going to debug before asking to merge this.

Error: unable to read git repository './' (are you sure it's a git repo?): exit status 128

I have no idea what is going on here. Could be a depth cloning issue.

I had to add fetch-depth to vacuum the other day.

    steps:
      - name: Checkout code
        uses: actions/checkout@v4
        with:
          fetch-depth: 50
          fetch-tags: true
          show-progress: true

[felixjung]

It was indeed the fetch depth. Pretty annoying. I still ended up adding some code that I think makes the parsing of positional args a bit more robust. I see that code is duplicated across the different commands. Should I extract into a function and apply it everywhere?

[daveshanley]

It was indeed the fetch depth. Pretty annoying. I still ended up adding some code that I think makes the parsing of positional args a bit more robust. I see that code is duplicated across the different commands. Should I extract into a function and apply it everywhere?

If you have the time? Always appreciated.