Exclude headref from selected branches #344
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This is helpful to users to better understand which target branches have been determined to backport to.
If we want to exclude the headref from the possible target branches, we need to provide it as a parameter to the findTargetBranches function. I'm not so happy that this affects all previously written unit tests for this function, but it is acceptable because headref has now become important for this function.
This case is relevant where the target_branches input is used to select
the target branches, and the original pull request's headref is part of
it.
For example, consider selecting all feature branches `feature/*` as
target_branches. Glob patterns are not supported yet, but users can find
these with an additional step in their workflow:
```
run: |
branches=$(git branch --list --all | grep 'origin/feature/' | cut -c 18- )
space_delimited=${branches//$'\n'/ }
echo "BRANCHES=${space_delimited}" >> $GITHUB_OUTPUT
```
Note that such a step requires a deep checkout `depth=0`.
But when users do this, they might encounter the feature branch they
just merged, the merged branch that triggered the backport-action.
By excluding it now, we can better support this case. In addition, it
will help support glob patterns in the target_branches input in the
future.
The headref is excluded automatically. Since this is an explicit difference in behavior, it should be clearly documented to avoid surprises for users. As far as I know, there is no use case to backport a pull request to its headref. The cherry-pick would be interrupted because there are no changes which would result in empty commits. Typically, the git user get's to decide to skip these commits, or to abort the cherry-pick. This means that would not be any new commits, and we cannot open an empty pull request. So all of this doesn't work. The only thing left to do, is exclude the headref from the determined target branches.
korthout
added
the
backport release-v1.3
|
Backport action workflow was still disabled for #312, but that issue has been resolved already. I've re-enabled the workflow now. /backport |
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Successfully created backport PR for |
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This pull request enables users to select target branches more leniently.
When the action is triggered for a pull request, its headref should not be selected as target branch because it already contains the commits. There is no use case to cherry-pick the changes to that same branch again. However, it was possible to select the headref both through labels matching the
labels_patterninput, as well as through thetarget_branchesinput. This pull request excludes the headref from any of the selected target branches automatically.One example where this could be useful was highlighted in #343. While glob patterns are not supported in the target_branches input yet, it is possible to expand a glob pattern in a separate step, like:
These branches can then be used as
target_branchesinput. However, if the headref is among the selected branches, the action would unsuccessfully attempt to cherry-pick the changes of the pull request onto that same pull request's head. Git would rightfully complain about this. Now, that no longer occurs.closes #343