feat: Flag to fetch the diff-base before diffing for if_changed#3689
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DrJosh9000 merged 4 commits intomainfrom Feb 2, 2026
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feat: Flag to fetch the diff-base before diffing for if_changed#3689DrJosh9000 merged 4 commits intomainfrom
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Description
if_changedassumes that both the diff-base exists locally and is reasonably up-to-date; for some branches this has a reasonable chance of being true, but (especially if)--git-diff-basehas been set to some custom value then the probability drops quite a bit.This change adds a new flag,
--fetch-diff-base, with corresponding env varBUIDLKITE_FETCH_DIFF_BASE, that runsgit fetch -- remote refspecbefore doing the git diff.Open question
Should this new flag be enabled by default?
Context
Using this new flag would fix #3602
https://linear.app/buildkite/issue/PS-1469
https://linear.app/buildkite/issue/PS-1595
Changes
Testing
go test ./...). Buildkite employees may check this if the pipeline has run automatically.go tool gofumpt -extra -w .)Disclosures / Credits
I did not use AI tools at all