facetted geom_smooth() doesn't work

[cpsievert]

d <- diamonds[sample(nrow(diamonds), 1000), ]
p <- qplot(carat, price, colour=cut, data=d) +
  facet_wrap(~cut) +
  stat_smooth(method=lm)
p

Here is the plotly result

[cpsievert]

This is the real problem with the example in #190. That issue is more of a question in how to implement ribbons in geom_smooth() (which would be nice to know before solving this).