facet_grid free space calculations incorrect

[hadley]

da <- data.frame(
  x = rep(1:5, 2),
  y = c(1+(0:4), 1+(0:4)/10),
  z = rep(1:2, each=5))

qplot(x, y, data=da, group=z, geom="line") +
  facet_grid(z ~ ., scales="free_y", space="free")

Panel two is about half the size it should be

[hadley]

Panel 1 has height 4.4 null units, and panel two has height 0.44 null units, so there's something I don't understand about how the grid layout works.

[hadley]

Fixed in d387066