- Add a permission check that the doer has write permissions to the head
repository if the the 'delete branch after merge' is enabled when
merging a pull request.
- Unify the checks in the web and API router to `DeleteBranchAfterMerge`.
- Added integration tests.
(cherry picked from commit 266e0b2ce9)
Conflicts:
tests/integration/pull_merge_test.go
trivial context conflict
Gusted