ERR: invalid time dimension offset: now()

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1

It looks like group by time with offset now() is deprecated. Is this accidentally removed or on purpose?

    select mean(value) from data where time > '2018-01-10T00:00:00Z' and time < now() group by time(18m, now)
    ERR: time dimension offset must be duration or now()
    > select mean(value) from data where time > '2018-01-10T00:00:00Z' and time < now() group by time(18m, now())
    ERR: invalid time dimension offset: now()