auto merge of #8677 : bblum/rust/scratch, r=alexcrichton

r anybody; there isn't anything complicated here

2 files changed, 8 insertions, 6 deletions

diff --git a/src/libstd/rt/comm.rs b/src/libstd/rt/comm.rs
index 5d55261a69d..8ef9c1332f9 100644
--- a/src/libstd/rt/comm.rs
+++ b/src/libstd/rt/comm.rs
@@ -499,13 +499,14 @@ impl<T> GenericPort<T> for Port<T> {
     }
 
     fn try_recv(&self) -> Option<T> {
-        let pone = self.next.take();
-        match pone.try_recv() {
-            Some(StreamPayload { val, next }) => {
-                self.next.put_back(next);
-                Some(val)
+        do self.next.take_opt().map_move_default(None) |pone| {
+            match pone.try_recv() {
+                Some(StreamPayload { val, next }) => {
+                    self.next.put_back(next);
+                    Some(val)
+                }
+                None => None
             }
-            None => None
         }
     }
 }
diff --git a/src/libstd/rt/mod.rs b/src/libstd/rt/mod.rs
index db1bfdf1bf5..8b3e65b57ab 100644
--- a/src/libstd/rt/mod.rs
+++ b/src/libstd/rt/mod.rs
@@ -323,6 +323,7 @@ fn run_(main: ~fn(), use_main_sched: bool) -> int {
     // task tree, shut down the schedulers and set the exit code.
     let handles = Cell::new(handles);
     let on_exit: ~fn(bool) = |exit_success| {
+        assert_once_ever!("last task exiting");
 
         let mut handles = handles.take();
         for handle in handles.mut_iter() {