Last Green Tag First: Bisect an OSS Regression Before the Patch Review

说明与用途

将最后的稳定版本视为控制组，验证 HEAD 并使用 git bisect 与确定性 oracle 精确定位导致回归的提交，从而减少不必要的代码更改并加速审查。

问题

Contributors often patch HEAD based on issue titles, leading to unnecessary changes and reviewer burden when the regression actually originates from an earlier commit.

结果

The workflow reduces unnecessary code changes, speeds up reviews, and provides a clear, reproducible artifact (bisect log) that reviewers can replay.

工作流

• 1. Verify the last release tag passes the oracle; if not, the issue is not a regression.
• 2. Verify HEAD fails the oracle; if not, the bug is not present.
• 3. Run git bisect with a deterministic oracle script to locate the bad commit.
• 4. Record the bisect log and add git show --stat and git tag --contains output to the PR.
• 5. Use the bisect log as evidence for reviewers to replay the test without local setup.

证据

A well‑meaning contributor asked a coding model for a patch and received a thirty‑line rewrite of the process launcher.

来源

The script below is meant to live on the topic branch, or to be pasted into the pull request body.

来源