[11u] Proposal: Switch jdk11u development to Git/Skara with 11.0.13 cycle

[Langer, Christoph]

Hi Vladimir,

> so the old process, with hg:
> if backport applies cleanly - do request to backport via jbs, once approved -
> push it to the repo, preserving original patch metadata (author, etc)
> 
> new process with skara:
> if backport appliess cleanly - create pull request, if bot decides its clean - can
> be integrated without review, then get approval via jbs, then integrate
> if backport does not apply cleanly - create pull request, wait for it to be
> reviewed, then get approval via jbs, then integrate
> 
> issue1: it’s bot who decides if this a clean backport or not, almost clean ==
> not clean

When we had a call with the Skara team, we talked about this point. For the case when the bot doesn't identify a backport as clean but we'd usually argue that it's a clean backport since e.g. only copyright headers changed or similar, we asked for a command to override the bot's decision. E.g. comment the PR with "/clean" or something like that. I don't know how the status of this development item is, though.

Anyway, even if such a "/clean" command isn't available, I'd rather think this wouldn't mean a big slowdown. You'd just have to find some reviewer to approve the PR.

> issue2 ( small one): clean backport is pushed under the name of backporter,
> not original author

This is a change of paradigm with the Skara tooling. A backport is now always attributed to the backporter which is something that several people involved in JDK updates backporting were asking for. So I wouldn't consider that as an issue, rather an improvement.

> when we only started with skara on jdk13u-dev, clean backports mechanics
> wasn’t existing yet, so every backport had to be reviewed, slowing us, now
> it’s a bit easier.
> 
> Skara is generally good for backports now. You may want to try to backport
> something into jdk13u-dev to test it yourself before you switch jdk11u-dev
> to git.

Thanks for your insights!

Cheers
Christoph