Bug report: Negative time

In this game that I was spectating in the moves bar it showed that some moves took negative time (e.g. -1.7)

I was just going to report that!

yup, I've seen this a while ago

Could you please report that using the sidebar item "Help" + "Report a Bug"? Thank you so much  

Thanks! I got the ticket! 

same. at first i thought it's just the real time witha minus added, but then i realized the time doesn't correspond to the real time WITHOUT the minus, too

also, different times are the same length

Were you lagging? Usually this error is lag related. 

I don't think its lag. I'm not having any lag now and this happened: (I was observing a game)

And on move 31, the time black took is blank!

I don't think so

I think this occur due to pre-moves, and this is not just occurring in beta version.

Maybe it is because of increment

Yes, its increment related; we figured that out and are working on it. 

Oh, the game was 15|2

no premoves only take 0.1 according to my calulation

yeah

Yes but if it's a premove with 2 second increment the amount of time that came OFF your clock is -1.9