Get Date/Time String unexpected rounding

I just noticed the function "Get Date/Time String" rounds to the nearest second when input "time stamp" is unwired, while it simply truncates when the input is wired.

I would expect the function to truncate in both cases.

I compared with "Format Date/Time String" for reference:

Fractional part > 0.5:

Fractional part < 0.5:

I guess it's a bug?

Regards,

Raphaël.