github.event.pull_request.base.sha not refering to base branching commit

[jeetee]

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As discovered in musescore/MuseScore#13992 (comment) and seemingly by someone else in actions/runner#1689 it seems that there is no way to get the actual base commit reference for a pull request.

While I can see the need for having a reference to the current head of the base branch, I would not expect this to be the value of github.event.pull_request.base.sha, but rather of an alternative (to be added?) property such as github.event.pull_request.base.head.sha or the likes.

As it stands, it seems to me that there is no way to have an easy test of only the PR changes (in our case, a visual reference test that should run between branch base reference and PR's HEAD).
Unless I'm somehow missing the obvious?

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[jeetee]

I guess what I'm hoping to find was something along the lines of git merge-base --fork-point <PR-merge-target>

[VanTanev]

I want to confirm that the issue exists.

We have a PR 2 that references PR 1's branch as its base branch. It is correctly shown in the github interface.

However, in github actions, github.event.pull_request.base.sha gives us the last commit on the repository main branch instead PR 1's latest commit.

[vol4onok]

I have the same issue. github.event.pull_request.base.sha gives another commit instead of git merge-base origin/currentbranch origin/master.

git merge-base origin/currentbranch origin/master - correct sha
github.event.pull_request.base.sha - The last commit

[magos1983]

same problem for me

[ovflowd]

However, in github actions, github.event.pull_request.base.sha gives us the last commit on the repository main branch instead PR 1's latest commit

You're looking for github.event.pull_request.head.sha

[brun0xff]

I'm facing the same problem here

[A132770]

I ran into this as well. I am trying to implement a type of status check that fails if a branch is not 'up-to-date' with main, to prevent subsequent more expensive status checks from running until main is merged in (GitHub's update feature does not prevent status checks from running).

[chrisconfirm]

anyone have an answer to this? i want to use pretty-quick, and have the same problem. i can not easily get the actual base commit reference. pretty-quick is therefore not finding any changes and not formatting any files. see prettier/pretty-quick#127

[Cowa]

I ran into this issue too. I'm using it for code coverage diff reports.