I have already done a preliminary review for you, and I hope to help you do a better job.

Based on the pull request title and description, it seems that the change is related to ignoring file changes while collecting log files. Looking at the diff, the change involves adding the --warning=no-file-changed flag to the tar command in two different files - pull_br_integration_test.groovy and pull_lightning_integration_test.groovy. This change should prevent the tar command from returning an error when there are no files to archive.

There doesn't seem to be any potential problems with this change. It's a simple change that shouldn't have any negative impact on the existing codebase.

However, it would be good to confirm if there were any issues related to the error returned by the tar command before making this change. Also, it would be beneficial to add some comments in the code explaining why this change was made.

As for fixing suggestions, I would suggest adding a comment in the code explaining why this change was made and how it resolves the issue. Additionally, the pull request description could be more detailed, explaining the problem that was encountered and how this change resolves it.

/hold

test on https://do.pingcap.net/jenkins/blue/organizations/jenkins/pingcap%2Ftidb%2Fpull_lightning_integration_test/detail/pull_lightning_integration_test/848/pipeline

/unhold

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