[cbartz]

Overview

Configure renovate to not rebase when a branch is behind main.

Rationale

Renovate does update a branch when configured to automerge.
The CI in this repository is quite expensive at the moment, triggering multiple integration test runs targetting real Openstack resources per every PR commit push.

When there are multiple PR's open, this increases the flakiness of the CI (e.g., the different PR executions compete with quota) and also leads to wasted CI runs (because only 1 PR "can win").

Checklist

• The charm style guide was applied.
• The contributing guide was applied.
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation for charmhub is updated.
• The PR is tagged with appropriate label (urgent, trivial, complex).
• The changelog is updated with changes that affects the users of the charm.
• The application version number is updated in github-runner-manager/pyproject.toml.

[Copilot]

Pull request overview

Configures Renovate to avoid automatically rebasing update branches when they fall behind main, reducing redundant CI runs and contention for expensive OpenStack-backed integration tests.

Changes:

• Set Renovate’s rebaseWhen behavior to never to prevent automatic rebases while keeping automerge enabled.