Creating plumbing branch

.github/workflows/sync.yml

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+name: Sync any source updates
+on:
+  workflow_dispatch:
+  schedule:
+  - cron:  '0 2 * * *'
+jobs:
+  update:
+    uses: overlookinfra/shared-actions/.github/workflows/sync.yml@main

README.md

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+# Mirrored repository
+
+This repository is synced from upstream on a regular basis.
+This default `plumbing` branch contains only the code to run the sync and this `README`.
+
+The other branches hold the actual code, and regular snapshots are taken and stored in the `backup/*` path.
+
+Change to the `main` or `master` branch to see the repo you probably expected.