Renovate doesn't prune branches which don't target default branch

[viceice]

Describe the proposed change(s).

Renovate doesn't prune branches, when they target a different base branch because it compares it with default branch for modifications.

renovate/lib/workers/repository/finalize/prune.ts

Lines 28 to 31 in fad3dc8

	const branchIsModified = await scm.isBranchModified(
	branchName,
	config.defaultBranch!,
	);

We need to pass the base branch for each renovate branch.

[renovate-release]

🎉 This issue has been resolved in version 38.77.2 🎉

The release is available on:

• GitHub release
• npm package (@latest dist-tag)
• 38.77.2

Your semantic-release bot 📦🚀