Update on join fails to find variable "immediate built" in `i`

[iagogv3]

Let me show a minimal reprex as it is easier than describe and I am not sure why does it happen:

> library(data.table)
> irisdt<-as.data.table(iris)
> var="Sepal.Length"

Next works

> aux <- irisdt[, .(var = min(var)), env = list(var = var), by = Species]
> irisdt[, !c("Sepal.Length")][aux, on = "Species", SLM := var, env = list(var=paste0("i.", var))][]
     Sepal.Width Petal.Length Petal.Width   Species   SLM
           <num>        <num>       <num>    <fctr> <num>
  1:         3.5          1.4         0.2    setosa   4.3
  2:         3.0          1.4         0.2    setosa   4.3
  3:         3.2          1.3         0.2    setosa   4.3
  4:         3.1          1.5         0.2    setosa   4.3
  5:         3.6          1.4         0.2    setosa   4.3
 ---                                                     
146:         3.0          5.2         2.3 virginica   4.9
147:         2.5          5.0         1.9 virginica   4.9
148:         3.0          5.2         2.0 virginica   4.9
149:         3.4          5.4         2.3 virginica   4.9
150:         3.0          5.1         1.8 virginica   4.9

But if I do not use auxiliary variable aux and I include the summarised datatable in i, I get

> irisdt[, !c("Sepal.Length")][irisdt[, .(var = min(var)), env = list(var = var), by = Species], on = "Species", SLM := var, env = list(var=paste0("i.", var))]
Error in .checkTypos(e, names_x) : 
  Object 'i.Sepal.Length' not found amongst [Sepal.Width, Petal.Length, Petal.Width, Species]