issue 3451: scale_manual throws unexpected error when na.values given and insufficient values provided
The case 1 and 2 of the following did not work at that time. But, then insufficient values are allowed now. So, none of the following errors now.
df <- data.frame(x = 1, y = 1:3, z = factor(c("a","b", NA), exclude = NULL)) p <- qplot(x, y, data = df, colour = z)