Harden Streamlined Build workflow against intermittent download and nbd-lock failures

[Copilot]

Recent "Streamlined Build" CI runs failed intermittently. Investigation of the run logs turned up two distinct causes.

Root causes

• Download step: curl exits 56, 92, and 28 (recv error, HTTP/2 stream error, timeout) hitting download.mikrotik.com. A prior fix bumped timeouts, which only covers exit 28 — curl's default --retry doesn't retry the other error classes, so those runs failed outright.
• "Convert images" step: qemu-img: Could not open 'chr-efi.qcow2': Failed to get shared "write" lock. Race condition — qemu-nbd -d returns before the kernel finishes releasing the file lock on the qcow2 image, so the immediately-following qemu-img convert sometimes loses the race.

Changes (.github/workflows/auto.yaml)

• Download step: add --retry-all-errors (with increased retry count/delay) so curl retries on any failure, not just its default transient-error subset.
• Disconnect ndb step: after qemu-nbd -d, poll /sys/class/block/<dev>/pid until each device is fully torn down before moving on to image conversion, removing the lock race.

- name: Download
  run: |
    curl -skL --retry 5 --retry-all-errors --retry-delay 5 --connect-timeout 10 --max-time 300 -o chr.img.zip ...

- name: Disconnect ndb
  run: |
    sudo -E qemu-nbd -d /dev/nbd0
    sudo -E qemu-nbd -d /dev/nbd1
    for dev in nbd0 nbd1; do
      for i in $(seq 1 10); do
        [ -f "/sys/class/block/$dev/pid" ] || break
        sleep 1
      done
    done

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[Copilot]

🟡 Changes recommended

NBD teardown timeout can still allow conversion to proceed while the lock remains.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

Harden the Streamlined Build workflow against transient downloads and NBD teardown races.

Changes:

• Expands curl retry handling.
• Polls NBD device teardown before image conversion.

File summaries

File	Description
.github/workflows/auto.yaml	Updates download retries and NBD cleanup handling.

Review details

• Files reviewed: 1/1 changed files
• Comments generated: 1
• Review effort level: Lite

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[Copilot]

Good catch — fixed. The loop now explicitly checks whether the sysfs pid file still exists after the 10s wait and fails the step with a clear error instead of silently falling through to the conversion step, so we no longer risk hitting the same lock race with a confusing downstream error.