[git-cherry-pick recipe] The example in docs produces a misleading result

I was following https://www.pygit2.org/recipes/git-cherry-pick.html#cherry-picking-a-commit-without-a-working-copy and it seemed to work at first but then I noticed that it pulls in extra commits that I've never wanted.

I think that this example is incomplete.

My src (https://github.com/sanitizers/patchback-github-app/blob/92934c6/patchback/event_handlers.py#L66-L133) should produce a branch with one cherry-picked commit but instead gets a whole bunch of earlier commits too: https://github.com/webknjaz/backport-test-repo/pull/13/commits.

从 docs/recipes/git-cherry-pick.html 中的配方开始，根据 issue 中描述的行为复现链接的 cherry-picking 示例。将结果与所引用的 event_handlers.py 源代码以及 backport-test-repo 的提交历史进行比较；当示例不再误导性地包含更早的提交，或清楚地解释观察到的结果时，文档就完成了。