Merge queue times out PRs whose checks are still running, so merging takes many manual attempts and CI is re-run from scratch #26292

Describe the bug

The merge queue regularly removes PRs with "removed this pull request from the merge queue due to no response for status checks" even though no check failed.

For example, #26244 is a 2-line change. It was approved on 2026-10-12 at 18:12 UTC. Since then it has been added to the merge queue 7 times by 4 different committers and removed 6 times.

In every case I looked at, checks had already passed and the rest had simply not finished (or started) within the hour. When the PR is added back to the queue, all of the CI runs again from the beginning, and often times out again.

This has been happening on and off for a while (see #23400 from September), but over the last two days (2026-10-13 and 2026-10-14) it affected most PRs that went through the queue.

Problems this causes

1. Merging an approved PR takes a long time and several manual steps

See above. Other recent examples of PRs that timed out in the queue (all eventually passed CI unchanged):

2. It burns a lot of CI capacity, because the tests do eventually finish but have to run again

Each timeout throws away CI work that already completed.

For each timeout, 22 jobs (65 to 88 runner-minutes of work) had already passed when the PR was evicted. When the PR is re-queued, those 22 jobs run again along with everything else.

For the 19 timeouts I checked on 10-13 / 10-14 alone, that is roughly 23 runner-hours of passing CI discarded in about 36 hours. We are already a top ASF consumer of GitHub Actions minutes:

• Reduce GitHub Actions usage (DataFusion is currently the top ASF consumer of GHA minutes) #25148

Even worse is that these timeouts also happen precisely when runners are scarce, so the re-runs add load at the worst possible time and make the next timeout more likely.

Expected behavior

A PR whose checks are all passing, just slowly, should merge without anyone having to touch it again. CI work that has already passed for a queue entry should not be discarded and redone.

Additional context

• The queue's status check timeout is currently 60 minutes (the GitHub default); the evictions above all happened 60 to 80 minutes after the queue built the entry.
• Related: CI: Merge queue rejects PR even after all tests pass #23400 (earlier queue evictions, closed),
• CI takes hours to start #25088 (CI takes hours to start),
• Reduce GitHub Actions usage (DataFusion is currently the top ASF consumer of GHA minutes) #25148 (reduce GitHub Actions usage)
• Enable merge queue in github to avoid commit confliction. #6880 (original merge queue discussion).