A continuation of the travails from
JENKINS-15816. If the timezone is changed after startup, it can happen that a job has some older builds with the old timezone that appear newer than the actually newest builds. Thus the RunMap gives an inconsistent picture (rm.values().iterator().next() != rm.iterator().next()), the last build may be older than the last successful build, BuildHistoryWidget may omit builds, etc.
The proper fix is perhaps to start using UTC for build records and switch to a new Run.id format that ends with Z or otherwise distinguishes builds created after the switch from historical builds. The question is what plugin code might be relying on the current format.