RFR: 8320358: GHA: ignore jdk* branches

[Magnus Ihse Bursie]

On Tue, 21 Nov 2023 14:42:07 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> At some point we are likely to use stabilization branches in the mainline jdk repo rather than a separate repo. In preparation, this PR excludes branches matching `jdk*`, like we currently do for `master` and `pr/*`.
> 
> A potential drawback of doing this is that it will exclude developer branches named `jdk-8888888` or similar, using a lower-case `jdk`. Developers who want a GHA run will need to use `JDK` (uppercase) or some other prefix.
> 
> This is unlikely to be a problem in practice. I checked the most recent 100 open pull requests in the `jdk` repo at the time I created this fix, and while many of them use "JDK" (upper case) as a prefix, I found none that use "jdk" (lower case).
> 
> 
> #### Testing
> 
> I pushed the following branch that was even with `jdk:master` at the time I pushed it (thus without this fix). GHA was run as expected:
> 
> * [jdk-8000000](https://github.com/kevinrushforth/jdk/tree/jdk-8000000) : [GHA run](https://github.com/kevinrushforth/jdk/actions/runs/6910232226) (NOTE: once this fix is integrated, such a branch would not get a GHA run)
> 
> 
> I pushed the following branches that all include this fix. GHA runs were skipped on the branches that start with `jdk` and run on the others:
> 
> * [JDK-8320358](https://github.com/kevinrushforth/jdk/tree/JDK-8320358) : [GHA run](https://github.com/kevinrushforth/jdk/actions/runs/6910192534), (you can also see this from this PR's test results)
> * [gha-exclude-jdk](https://github.com/kevinrushforth/jdk/tree/gha-exclude-jdk) : [GHA run](https://github.com/kevinrushforth/jdk/actions/runs/6910204060)
> * [jdk12345](https://github.com/kevinrushforth/jdk/tree/jdk12345) : No GHA run
> * [jdk-8320358-gha](https://github.com/kevinrushforth/jdk/tree/jdk-8320358-gha) : No GHA run

> Yes, but the fact I can come up with an easy example where it breaks serves as signal there are likely less obvious broken cases :)

I mean, absolutely there can be other things, unknown to us, that will break. Just as adding the `pr/*` could have caused breakage. But this is the case for all code changes, especially for stuff like this that can run in diverse environment.

I don't think that should stop us, however. The better the reason to reserve the entire jdk name space already, instead of finding out later on that we need to redo the entire thing just because someone decided that jdk30 is actually going to be called "Java3"... (You're laughing? Remember Java2 ...)

However, we might want to document somewhere that branches with a name that starts with `jdk` or `pr/` will not be tested by GHA.

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PR Comment: https://git.openjdk.org/jdk/pull/16763#issuecomment-1821224058