fix(scripts/lint-packages): use package directory for version diff check

[TomJo2000]

and try to work out the issue causing git merge-base to not find the base commit of a PR branch.

• Test commit based on fix(x11/cinnamon): use desktopappinfo from giounix not gio #26744's original version which ran into the edgecase.

[robertkirkman]

I tested this in

• #26754

I think this is working.

[TomJo2000]

I did a similar test above (based on #26744's initial issue) but I had already cleaned up the commits on this branch.
https://github.com/termux/termux-packages/actions/runs/18201628698/job/51821761405?pr=26750#step:5:26

[robertkirkman]

I was testing what would happen if the name of the PR branch was "master", but I didn't see anything wrong happen as far as I can tell.

[TomJo2000]

Ah yeah that makes sense.
That's accounted for since we're reading .git/refs/remotes/origin/master.
Whereas the PR's branch is at .git/refs/remotes/pull/${PR_number}.
And local master is at .git/refs/heads/master.

[robertkirkman]

I have determined in wild (downstream project's GitHub Actions CI) that this change has a dependency on this line, because this line uses git fetch origin master. After this change, if this lint-packages.sh is ever used in a CI workflow that was in a PR but did not have git fetch origin master already somewhere in it, there will be an error.

termux-packages/.github/workflows/packages.yml

Line 85 in 5abfc71

if [[ "${{ github.event_name }}" == "pull_request" && -n "$(git rev-list --merges "$(git fetch origin master >&2; git merge-base origin/master $HEAD_COMMIT)..$HEAD_COMMIT")" ]]; then

maybe that's not very important, since official termux-packages CI has that line, but I thought it important to write this note in case this change confuses anyone else or anyone else encounters the problem.