RETARGET_CHILDREN_ON_MERGE retargets branches to the main branch instead of the target of the parent branch

[Zermelo-Ulbe]

Description

When closing a branch in the middle of a PR chain, the target of the child PR is reset to the main branch instead of the target of the parent PR. This behavior has changed since 1.23.X.

The config cheat sheet says the target of the child branch should be set to the target of the parent branch:

RETARGET_CHILDREN_ON_MERGE: true: Retarget child pull requests to the parent pull request branch target on merge of parent pull request. It only works on merged PRs where the head and base branch target the same repo.

Reproduction

• Start Gitea with RETARGET_CHILDREN_ON_MERGE: true
• Create four branches and main: main, notmain, 1, 2, 3
• Create a PR from 3 into 2, from 2 into 1, and from 1 into notmain
  • notmain < 1 < 2 < 3
• Merge the PR from 2 into 1
  • Expected: notmain < 1 < 3
  • Actual: notmain < 1 and main < 3

Repro at https://demo.gitea.com/Zermelo-Ulbe/demo/pulls/3

Gitea Version

1.24.3

Can you reproduce the bug on the Gitea demo site?

Yes

Log Gist

No response

Screenshots

Git Version

No response

Operating System

No response

How are you running Gitea?

Issue occurs on https://demo.gitea.com/

Database

None