https://ubuntu-archive-team.ubuntu.com/proposed-migration/log/noble/2024-01-12/23:28:17.log.gz shows that libwacom is in the 'autopkgtest-pending.json' for amd64 and s390x.  So that's a bug, to start with.

(We have a bug in general that state/autopkgtest-pending.json does not get properly garbage-collected, so grows without bound.  File is currently 112477 lines long.  There are 22,000 results marked as 'Test in progress' on update_excuses, but it's still excessive?)

A deep dive into https://ubuntu-archive-team.ubuntu.com/proposed-migration/noble/update_excuses.yaml.xz (which shows information that update_excuses.html hides, for browser performance reasons) shows:

- excuses:
  - 'Migration status for libwacom (2.8.0-1 to 2.9.0-1): BLOCKED: Rejected/violates
    migration policy/introduces a regression'
  - 'Issues preventing migration:'
  - 'Additional info:'
  - 4 days old
  - Not touching package as requested in <a href="https://launchpad.net/bugs/2049237">bug
    2049237</a> on Fri Jan 12 22:25:14 2024
  is-candidate: false
  item-name: libwacom
  maintainer: Timo Aaltonen
  migration-policy-verdict: REJECTED_PERMANENTLY
  new-version: 2.9.0-1
  old-version: 2.8.0-1
  policy_info:
    age:
      age-requirement: 0
      current-age: 4.585891203703704
      verdict: PASS
    autopkgtest:
      cinnamon-control-center/5.8.2-1:
        amd64:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/amd64/c/cinnamon-control-center/20240113_163413_fd9be@/log.gz
        - https://autopkgtest.ubuntu.com/packages/c/cinnamon-control-center/noble/amd64
        - null
        - null
        arm64:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/arm64/c/cinnamon-control-center/20240113_084446_18593@/log.gz
        - https://autopkgtest.ubuntu.com/packages/c/cinnamon-control-center/noble/arm64
        - null
        - null
        armhf:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/armhf/c/cinnamon-control-center/20240113_030203_158e7@/log.gz
        - https://autopkgtest.ubuntu.com/packages/c/cinnamon-control-center/noble/armhf
        - null
        - null
        ppc64el:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/ppc64el/c/cinnamon-control-center/20240113_120123_f31b7@/log.gz
        - https://autopkgtest.ubuntu.com/packages/c/cinnamon-control-center/noble/ppc64el
        - null
        - null
        s390x:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/s390x/c/cinnamon-control-center/20240112_191145_ac481@/log.gz
        - https://autopkgtest.ubuntu.com/packages/c/cinnamon-control-center/noble/s390x
        - null
        - null
      libinput/1.23.0-2.1:
        amd64:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/amd64/libi/libinput/20240113_163212_eefe2@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libi/libinput/noble/amd64
        - null
        - null
        arm64:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/arm64/libi/libinput/20240113_084221_c4aed@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libi/libinput/noble/arm64
        - null
        - null
        armhf:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/armhf/libi/libinput/20240113_025903_f671b@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libi/libinput/noble/armhf
        - null
        - null
        i386:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/i386/libi/libinput/20240112_191802_f671b@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libi/libinput/noble/i386
        - null
        - null
        ppc64el:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/ppc64el/libi/libinput/20240113_121112_d712f@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libi/libinput/noble/ppc64el
        - null
        - null
        s390x:
        - PASS
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/s390x/libi/libinput/20240112_191141_a75f6@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libi/libinput/noble/s390x
        - null
        - null
      libwacom/2.9.0-1:
        amd64:
        - ALWAYSFAIL
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/amd64/libw/libwacom/20240113_163456_db271@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libw/libwacom/noble/amd64
        - null
        - null
        arm64:
        - ALWAYSFAIL
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/arm64/libw/libwacom/20240113_084308_348cc@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libw/libwacom/noble/arm64
        - null
        - null
        armhf:
        - ALWAYSFAIL
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/armhf/libw/libwacom/20240113_025905_0cb24@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libw/libwacom/noble/armhf
        - null
        - null
        i386:
        - ALWAYSFAIL
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/i386/libw/libwacom/20240112_192325_dec21@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libw/libwacom/noble/i386
        - null
        - null
        ppc64el:
        - ALWAYSFAIL
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/ppc64el/libw/libwacom/20240113_121054_348cc@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libw/libwacom/noble/ppc64el
        - null
        - null
        s390x:
        - ALWAYSFAIL
        - https://autopkgtest.ubuntu.com/results/autopkgtest-noble/noble/s390x/libw/libwacom/20240112_191135_3dcde@/log.gz
        - https://autopkgtest.ubuntu.com/packages/libw/libwacom/noble/s390x
        - null
        - null

[...]

So britney is seeing this as an 'alwaysfail' result, meaning not a regression.

noble/state/autopkgtest-results.cache correctly labels the libwacom autopkgtest/2.8.0 results as 'NEUTRAL', not "FAILED".

So the issue is in the merging of the information about the old vs new states.