Simplify contrib/backport

[silverwind]

This script was trying to be too smart, make it more straightforward and less error-prone so that i could be used by the backport bot too ideally.

• Always delete the backport branch so that script is idempotent in this regard
• Remove the push functionality, it's best done by the user because only they know the remote name
• Remove reading docs/config.yaml, it no longer exists
• Remove version detection, version is now a required argument
• Remove opening the pull request with xdg-open, xdg-open is not portable
• Remove continue from failed cherry pick. It's best to reset manually in this case
• Clean up the console logging

Example run:

$ go run ./contrib/backport --version v1.21 27503
* Backporting 27503 to origin/release/v1.21 as backport-27503-v1.21
* `git fetch origin main`
* `git fetch origin release/v1.21`
* `git branch -D backport-27503-v1.21`
* `git checkout -b backport-27503-v1.21 origin/release/v1.21`
* Attempting git cherry-pick 08efeb5cdc22d21b5ef12cc540727594a22062d1
* Amending commit to prepend `Backport #27503` to body
Backport done! You can now push it with `git push yourremote backport-27503-v1.21`

[wxiaoguang]

Good to keep things simple

[zeripath]

This will break the --continue functionality.

[delvh]

Yes, that parameter was removed.
What exactly did that do?

[silverwind]

It did look for a aborted cherry-pick, but I think given that the script now deletes the backport branch every time, it likely will never encounter the situation again. I think it's good that this script becomes idempotent (it isn't so far because it stays on the backport branch after execution, but that's kind of a necessity because we now require the user to push).

Also, the command logging and error printing should be improved with a single shell execution wrapper function.

[silverwind]

The goal is to get this script into a state where the backporter bot can use it, so we can replace most of this code.

[zeripath]

It already was in a state that the backporter tool could use.

By removing the --continue option you've made it impossible to use the script to help create backports when there is a conflict.

--continue simply allowed you to fix the conflicts and then restart the process.

Instead of simply removing things you should have just read or improved the documentation explaining what it was doing.

[silverwind]

I don't mind if you want to restore, but I thought this script should be idempotent and a --continue did not fit into the concept. The bot would only do clean checkouts and if there is a merge conflict, it has to be resolved manually in any case.

[zeripath]

It cannot be idempotent. It was not intended to idempotent it was supposed to assist with performing backports especially when those backports failed.

[zeripath]

Your simplification has now broken the specific help information that gitea-backport tells maintainers.

e.g. #27511 (comment)

It said how to use the script, if it wasn't clear you should have improved the message instead of simply destroying things.

[silverwind]

Right, so let's restore --continue. We also need to adjust the message for --backport-branch which no longer has a default, I'd make that part of the argv, e.g. go run ./contrib/backport 1.21 27511 and include a line for the push.