This is the second time this has occurred recently: Jekins has failed because the timestamp generated by the code is one second off from the expected value, most likely because the code takes some time to run and the seconds hand of the clock might tick once in the mean time. example
A QUnit test for Echo has a race condition with a timestamp. The expected time and function results have a one second resolution and can divert:
Chrome 53.0.2785 (Linux 0.0.0) ext.echo.dm - mw.echo.dm.NotificationItem Constructing items FAILED Empty data (getTimestamp) Expected: "2016-12-15T13:54:41Z" Actual: "2016-12-15T13:54:42Z"