Improper alignment of boxplots in facets

Hi,
first of all, thanks for a great package!
I have spent some time with it recently and I think that I have found a bug. If I use boxplots and facets, the boxplots in the upper facet are on the left side of the category while the boxplots in the bottom facet are on the right side of the category, while I believe that they should be aligned in the middle. Picture tells more than thousands words, so see bellow...

you can get it with the following code:

library(ggplot2)
library(plotly)

data.1 <- diamonds
data.1$set <- "set1"

data.2 <- data.1
data.2$set <- "set2"

my.data <- rbind(data.1, data.2)

p <- ggplot(my.data, aes(x=cut, y=price, fill= clarity))+
  geom_boxplot()+
  facet_grid(set ~ .)

ggplotly(p)%>%
  layout(boxmode = "group")

Comece com a reprodução fornecida de ggplot2 e ggplotly, concentrando-se em como os boxplots facetados são convertidos e posicionados. Recrie o exemplo e verifique se os boxplots em ambas as facetas estão centralizados em suas categorias, preservando ao mesmo tempo o comportamento do layout agrupado.