fix: delta after merge is not working as expected

[DidZ0]

Fixes an issue where delta deployment after merging a PR isn't calculated correctly.

The issues seems to be the orientation of the delta calculation from "HEAD" to "HEAD^", generating destructive changes if the metadata is new.

inverting the references fixes the issue.

Thus, the way sfdx-git-delta is used while deploying, it will only generate the delta with the latest commit.
A temporary workaround would be to activate Squash Commits in the merge request.

[nvuillam]

@DidZ0 good catch !
The bug was probably never caught because of Quick Deploy always used after merge

I'm not the biggest git expert, are you 100% sure of your fix ?

[DidZ0]

@nvuillam
As far as I'm concerned this isn't even git related, it has more to do with the way sfdx-git-delta is working.
I'm pretty sure this fix is valid as we indeed want to find what is new from the last commit, not what is deleted / changed if we go back to the last commit.

CF https://github.com/scolladon/sfdx-git-delta?tab=readme-ov-file

From the project repo folder, the CI pipeline will run the following command:

sf sgd source delta --to "HEAD" --from "HEAD~1" --output-dir .

which means:
Analyze the difference between HEAD (latest commit) and HEAD~1 (previous commit), and output the result in the current folder.

This is what you're doing in the check-deploy since you're comparing from the first commit ID of the PR to the last one

[nvuillam]

@DidZ0 I generated an alpha version, please can you test with it and confirm that all is ok ? :)

Thanks :)

[DidZ0]

@nvuillam So far so good ! It is working as intended, the delta is the same pre and post deployment.
I know this is not a common use case but it would be great to have it.

[nvuillam]

@DidZ0 thanks for your feedback, you'll have it very soon, just the time i'm on a laptop 🥳