roll does not work with nanotime (integer64)

Start by reproducing the reported data.table joins using roll with nanotime, bit64/integer64, and POSIXct values. Compare the observed results with the expected rolling matches and verify the behavior for numeric, integer64, and time-based inputs; the issue names no source file or test to begin from.

Hello, I found the following bug where using roll and nanotime

library(data.table)
library(nanotime)
library(bit64)

X = data.table(t = c(0, 1))
Y = data.table(t = c(2, 9))

# expected nbehaviour
X[Y, on = .(t), .(x.t, i.t)]
     x.t   i.t
1:  NA   2
2:  NA   9
# roll expected behaviour
X[Y, on = .(t), .(x.t, i.t), roll = 1]
   x.t    i.t
1:   1     2
2:  NA   9

options(nanotimeFormat = "%Y-%m-%dT%H:%M:%E9S")
X = data.table(t = nanotime(c("2020-01-02T16:34:58.393243640", "2020-01-02T16:34:58.393243641")))
Y = data.table(t = nanotime(c("2020-01-02T16:34:58.393243642", "2020-01-02T16:34:58.393243649")))

# usual nonsense for NA but correct
X[Y, on = .(t), .(x.t, i.t)]
                             x.t                           i.t
1: 2262-02-18T20:47:17.227407266 2020-01-02T16:34:58.393243642
2: 2262-02-18T20:47:17.227407266 2020-01-02T16:34:58.393243649

# I think incorrect
>  X[Y, on = .(t), .(x.t, i.t), roll = 1]
                             x.t                           i.t
1: 2020-01-02T16:34:58.393243641 2020-01-02T16:34:58.393243642
2: 2020-01-02T16:34:58.393243641 2020-01-02T16:34:58.393243649

# I think incorrect
>  X[Y, on = .(t), .(x.t, i.t), roll = as.integer64(1)]
                             x.t                           i.t
1: 2020-01-02T16:34:58.393243641 2020-01-02T16:34:58.393243642
2: 2020-01-02T16:34:58.393243641 2020-01-02T16:34:58.393243649

# Same with POSIXct

X = data.table(t = as.POSIXct(c("2020-01-02 16:34:58.390", "2020-01-02 16:34:58.391"))) 
Y = data.table(t = as.POSIXct(c("2020-01-02 16:34:58.392", "2020-01-02 16:34:58.399"))) 
X[Y, on = .(t), .(x.t, i.t), roll = 0.001]                                              
                       x.t                     i.t                                                 
1: 2020-01-02 16:34:58.391 2020-01-02 16:34:58.391                                                 
2:                    <NA> 2020-01-02 16:34:58.398                                                 

Note:
linked to https://stackoverflow.com/questions/58916594/why-does-min200-300-returns-300-for-integer64-class ?
Edit 2020-06-25
probably unlinked