JENKINS-9913 is covering only the reporting of checkpoints, this should be reopened: JUnitResultArchiver.CHECKPOINT still exists, and probably should not.
Needs to be determined if anything needs to be done to replace it, in case a build with a higher number in fact finishes before one with a lower number, so calculation of test regressions cannot be done accurately when the result is published (in case anyone even cares about build-to-build diffs for a concurrent-capable job). Until the earlier build finishes, will the later build’s test result display show any “regressions” (against the last completed build), or show no regressions ever, or throw exceptions? After the earlier build finishes, will the later’s result display show regressions against the earlier build, or against the last completed build at the time of this build’s completion, or do something else? In other words, are calls to getPreviousResult made on demand whenever a build-to-build diff is requested (great)? Or made once when the build completes (not great but adequate)? Or does something really break? My casual inspection of the code suggests that there is some improper caching (CaseResult.failedSince) but that code generally defends against a prior build having no test result action, meaning that simply deleting CHECKPOINT would cause little harm.