RFR: 1706: Store github checks in PR unique way [v2]

[Zhao Song]

On Fri, 10 Feb 2023 17:11:53 GMT, Zhao Song <zsong at openjdk.org> wrote:

> > From the link you provided, I notice there are three items `jcheck`, `jcheck-openjdk/playground-125` and `jcheck-openjdk/playground-126` under the `openjdk`. And the `PR-125`, which is sooner than `PR-126`, also has these three items, please see https://github.com/openjdk/playground/pull/125/checks.
> 
> That's a good point and the kind of thing I wanted to catch by testing it in staging. This is caused by testinfo bot copying all checks from the source branch into the pull request. This copying will need to be filtered so that only the relevant jcheck checks are copied.

After testing, I realized that just filtering is insufficient for GitHub as checks in pull requests are same as checks in source commits(There is no need to copy). To display only relevant checks, we may need to store checks separately under the source commit.

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PR: https://git.openjdk.org/skara/pull/1470