Changed files wrong due to inclusion of merge commits

[dillydill123]

I'm using the changed files as so:

jobs:
  - job: check_changed_files
    displayName: Check changed files
    steps:
      - checkout: self
        fetchDepth: "0"
      - task: ChangedFiles@1
        name: check_changed_files_task
        inputs:
          ${{ if eq(variables['Build.Reason'], 'PullRequest') }}:
            refBranch: $(System.PullRequest.TargetBranch)
          rules: |
            [DocsChanged]
            arch/doc/**
            [ArchitectureChanged]
            **/*.yaml

In the case where it is not a pull request, i.e. a merge happens to develop. I noticed it is including a lot more files. I think what's occurring is that users who merge develop into their feature branch, then merge their feature branch back into develop have this issue. These merge commits are checked with the git log command to see which files changed, producing more files changed.

Does this seem like the current behavior? Or am I using the extension wrong?

[dillydill123]

Ok, after further investigation, it doesn't seem to be related to merge commits. I created a PR with one commit and merged it immediately after. It still has the issue where it is including many commits that were not included as part of my merge. This causes many more files to be included. During the pull request, this worked fine. It's only the case when it's not a pull request. Based on this, it seems that I might not be using the extension correctly?

[dillydill123]

After more investigation it seems I was confused by what the extension does. I looked at the getBuildChanges API to understand it better. Is there a way to specify just the changes from the files that were merged from a PR? Basically, if a merge happens to develop occurs, I want to have changed-files check only the files that were updated from that PR that was merged, and not from a previous build. Could I do something like develop~1 perhaps?