rand: bubble up IO messages futher.

The various ...Rng::new() methods can hit IO errors from the OSRng they use,
and it seems sensible to expose them at a higher level. Unfortunately, writing
e.g. `StdRng::new().unwrap()` gives a much poorer error message than if it
failed internally, but this is a problem with all `IoResult`s.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libstd/rt/task.rs b/src/libstd/rt/task.rs
index ededc69c5a1..abaa91b12f8 100644
--- a/src/libstd/rt/task.rs
+++ b/src/libstd/rt/task.rs
@@ -434,7 +434,7 @@ mod test {
     #[test]
     fn rng() {
         use rand::{StdRng, Rng};
-        let mut r = StdRng::new();
+        let mut r = StdRng::new().unwrap();
         let _ = r.next_u32();
     }