RFR: Section on backporting [v5]

[Andrew Haley]

On Wed, 24 Nov 2021 17:42:44 GMT, Jesper Wilhelmsson <jwilhelm at openjdk.org> wrote:

>> Guidance on backporting.
>> Also moved "Backing out a change" to the testing section where I believe it fits better. This section is unchanged.
>
> Jesper Wilhelmsson has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Updated todo-list

src/index.md line 1375:

> 1373: ## Backing Out a Change
> 1374: 
> 1375: If a change causes a regression that can't be fixed within reasonable time the best way to handle the regression can be to back out the change. Backing out means that the inverse (anti-delta) of the change is pushed to effectively undo the change in the repository. There are two parts to this task, how to do the bookkeeping in JBS, and how to do the actual backout in git or mercurial.

Suggestion:

If a change causes a regression that can't be fixed within reasonable time, the best way to handle the regression can be to back out the change. Backing out means that the inverse (anti-delta) of the change is pushed to effectively undo the change in the repository. There are two parts to this task, how to do the bookkeeping in JBS, and how to do the actual backout in git or mercurial.

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PR: https://git.openjdk.java.net/guide/pull/66