[ci] Fix files_changed merge main issues and files_changed and check_bazel script's base_sha to point to HEAD~1

[pablo-guardiola]

Follow up from #24 and #28

This PR fixes:

• https://github.com/bitdriftlabs/capture-sdk/actions/runs/10781042749/job/29898099793 👇

Check for workflow file changes
Run ./ci/files_changed.sh .github/workflows/android.yaml
fatal: ambiguous argument 'origin/': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
No relevant changes found.

Check for relevant Gradle changes
Run ./ci/files_changed.sh "^platform/jvm/gradle-test-app/.*\.(gradle|kts|kt|xml)$"
fatal: ambiguous argument 'origin/': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
No relevant changes found.

This is solved by fixing files_changed to differentiate when you are in a PR or main, as well as ensuring git diff failures are caught and reported accordingly.

• check_bazel and files_changed script's base_sha to point to HEAD~1 when running on a main merge. I noticed that no changes were detected even though they were present as part of the PR. Root cause was that we were diffing pointing to the same references and hence no changes. Pointing to the commit before the current one (HEAD~1) fixes this. I've thoroughly tested locally and now changes are detected too after merging a PR.

cc @murki

[murki]

Thanks @pablo-guardiola , would you mind add some inconsequential code change somewhere that would be picked-up by files_changed.sh to verify it works? I can then approve and run the checks

[pablo-guardiola]

@murki

would you mind add some inconsequential code change somewhere that would be picked-up by files_changed.sh to verify it works? I can then approve and run the checks

I already did that locally but I can push some "empty" changes for you to double check, not a problem.

It's important that the changes land on main to test if everything works after merging PRs and I didn't want to pollute the repo's commit history ¯\_(ツ)_/¯

But you can probably remove them quickly after confirming 👍

[murki]

this might break detekt, plus I agree with your statement about not polluting the repo with these changes and the TODOS since they will go into main. How about something inconsequential that can actually stay in teh codebase? Something like a variable rename for example

[pablo-guardiola]

Sounds good to me. Let me quickly fix 👍

[pablo-guardiola]

Done 👉 ecd11ac