geom_step truncating line too early before null value #532

It seems that geom_step is truncating the line too early when it encounters a null value. Rather than continue the line until the null value, it stops at the prior value:

Example:
ggplot(data.frame(x=1:5, y=c(1,2,NA,1,1)), aes(x,y)) + geom_step()

Plain ggplot2:

Plotly: