CI: verify-backported-commits.sh is broken

[cuviper]

In #88946, @Mark-Simulacrum suspected that I was going to fail CI for lack of backport-of in my new beta commit. But in the check runs, the test "passed" with this output:

Run src/ci/scripts/verify-backported-commits.sh
  src/ci/scripts/verify-backported-commits.sh
  shell: /bin/bash --noprofile --norc -e -o pipefail {0}
  env:
    CI_JOB_NAME: x86_64-gnu-tools
    SCCACHE_BUCKET: rust-lang-ci-sccache2
    TOOLSTATE_REPO: https://github.com/rust-lang-nursery/rust-toolstate
    CACHE_DOMAIN: ci-caches.rust-lang.org
    CI_ONLY_WHEN_SUBMODULES_CHANGED: 1
    IMAGE: x86_64-gnu-tools
fatal: unknown commit 53fd98ca776cb875bc9e5514f56b52eb74f9e7a9
All commits in `HEAD` are present in `master`

That unknown commit is the BETA_LIMIT at the top of the script, not mine.

[yaymukund]

Sorry about that, I wrote the script but did not see this until just now, a year later 😓

Is this still an issue? Has the script been useful / would it be worth taking another look?

[Mark-Simulacrum]

I think we have had pretty good success just holding ourselves to a higher bar of forward-porting to master when needed, so I think there's not been a problem from not having the script (and in practice it does impose some cost). I think for now we don't need to fix it.

My current hope is that we will migrate backports to be largely generated either automatically (by triagebot) on PR tagging, which will make overhead of such tracking lower and perhaps motivate closing the loop by requiring annotation for manually ported commits.