`new_scale` modifies the ggplot object about ggnewscale HOT 7 CLOSED

library(ggplot2)
library(ggnewscale)
topography <- expand.grid(x = 1:nrow(volcano), y = 1:ncol(volcano))
topography$z <- c(volcano)

## create two equivalent ggplot objects
p0 <- ggplot(mapping = aes(x, y)) + geom_contour(data = topography, aes(z = z, color = stat(level))) + scale_color_viridis_c(option = "D")
p <- ggplot(mapping = aes(x, y)) + geom_contour(data = topography, aes(z = z, color = stat(level))) + scale_color_viridis_c(option = "D")

p + new_scale_colour()
#> Registered S3 method overwritten by 'ggedit':
#>   method from   
#>   +.gg   ggplot2

all.equal(p, p0)
#> [1] TRUE