BUG: gf_violin not showing quantile lines

I think this might be a bug. These two commands should be equivalent (I think??) but only the first shows quantile lines:

ggplot(mtcars, aes(x = 1, y = mpg)) + 
  geom_violin(quantile.linetype = "solid")

gf_violin(mpg~1, data = mtcars, 
          quantile.linetype = "solid")

ggplot2 did change how quantile lines get drawn a while ago; something seems to be getting lost in translation now...