Is there a bug with setDate() ?

I'm having a problem using setDate() and there appears to be a bug. Here's some simplified code to try:

var x=0;
setInterval(function(){digitalWrite(LED1,x); x=!x;}, 500);

console.log(getTime());

//setTime(1000); 

console.log(getTime());

This works as expected - the red LED flashed every 500ms.

Now uncomment the setTime(1000) and try again - the Time is not set and the interval stops working!

I need to power Espruino off/on to get timer functions working again - not even a reset() helps.