CI flake: Test Suite

[clockwork-labs-bot]

Detected by CI Gremlin after a failed merge-queue run succeeded in a later merge-queue run without a new PR head commit.

Tests:

• Test Suite

Error:
fatal: couldn't find remote ref refs/heads/gh-readonly-queue/master/pr-5574-0935d323c64d9efd576bdf210982b8f4d7047883
The process '/usr/bin/git' failed with exit code 128

Failed job runs:

• https://github.com/clockworklabs/SpacetimeDB/actions/runs/30316929206/job/90144846297 (Test Suite, attempt merge queue run 30316929206 -> merge queue run 30319055901)

Timeout detection:

• none

Context:

• Merge queue PR: Scheduled reducer: use timestamp from reducer params for next run #5574
• PR head SHA: 0935d32
• Later successful run: https://github.com/clockworklabs/SpacetimeDB/actions/runs/30319055901

[clockwork-labs-bot]

Diagnosis for the linked exact job/attempt:

• Public run/job: clockworklabs/SpacetimeDB run 30316929206, job 90144846297, Test Suite, attempt 1.
• Context from the ticket/run: merge queue for PR Scheduled reducer: use timestamp from reducer params for next run #5574, PR head SHA 0935d323c64d9efd576bdf210982b8f4d7047883; failed merge-group run head branch gh-readonly-queue/master/pr-5574-0935d323c64d9efd576bdf210982b8f4d7047883, head SHA 9aebf24d8a040268cb0549f2cfbc71fbe9e7c0e9.
• The job failed in actions/checkout@v4 before the Test Suite started.
• Checkout retried the merge-queue branch fetch three times and failed with:
  • fatal: couldn't find remote ref refs/heads/gh-readonly-queue/master/pr-5574-0935d323c64d9efd576bdf210982b8f4d7047883
  • The process '/usr/bin/git' failed with exit code 128

Root cause for this exact attempt: the merge-queue synthetic branch was no longer fetchable during checkout. This is a merge-queue ref lifetime/checkout infrastructure failure before any Test Suite code ran.

Suggested updated title:

CI infra flake: merge-queue checkout could not fetch gh-readonly-queue ref

Duplicate check in the Test Flakes tickets:

• CI flake: Smoketests (Linux) #5597 is the closest duplicate candidate: same failed merge-queue run, same missing gh-readonly-queue/master/pr-5574-... ref, same actions/checkout@v4 failure before job-specific tests.
• CI flake: Keynote Bench #5599 is the same signature in Keynote Bench.
• CI flake: internal compiler error building libssh #5596 is from the same merge-queue run but failed later with a distinct libssh2-sys compiler ICE, so it is not a duplicate.
• I did not find an older Test Flakes ticket with this exact missing merge-queue ref checkout signature.

Top duplicate candidate: #5597.

[clockwork-labs-bot]

Correction: #5308 is the older open duplicate for this failure mechanism.

The failure here is the same merge-queue checkout infrastructure issue as #5308: actions/checkout could not fetch a gh-readonly-queue/... ref and failed with fatal: couldn't find remote ref before any job-specific tests or benchmarks ran.

My earlier duplicate search missed #5308 and incorrectly said no older Test Flakes ticket existed. Top duplicate candidate should be #5308. I am leaving this ticket open because #5308 is not on the proactive auto-close allowlist (#3285, #3290, #3099 only), unless a human asks me to close it.