RFR: 1463: Include starting branch in back port instructions [v3]

[Magnus Ihse Bursie]

On Sun, 7 Aug 2022 22:45:58 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Guoxiong Li has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Tweak the message again.
>
> Sorry but I find this new step creates confusion. Would it normally be subsumed by using `git sync`?

@dholmes-ora The JBS report by Mikael says that an important step is missing -- we need to make sure we start with an up-to-date view of the target branch. This aspect was missing from the instructions before. It seem to me that @lgxbslgx's patch will add this. Of course adding more instructions adds to the complexity, but that is the price to pay to get a fail-safe process.

At the risk of being more verbose, the instructions could possibly be made clearer, by listing the additions as a separate step, like:
"First make sure you have an up to date revision of the target branch:
$ git checkout..
$ git fetch --no-tags ...

Then  get this backport PR:
..."

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PR: https://git.openjdk.org/skara/pull/1344