Unsupervise tasks before the scheduler kills them. Unblock before yield->fail

src/rt/rust_scheduler.cpp

@@ -81,10 +81,14 @@ rust_scheduler::kill_all_tasks() {
     scoped_lock with(lock);
 
     for (size_t i = 0; i < running_tasks.length(); i++) {
+        // We don't want the failure of these tasks to propagate back
+        // to the kernel again since we're already failing everything
+        running_tasks[i]->unsupervise();
         running_tasks[i]->kill();
     }
 
     for (size_t i = 0; i < blocked_tasks.length(); i++) {
+        blocked_tasks[i]->unsupervise();
         blocked_tasks[i]->kill();
     }
 }

src/rt/rust_task.cpp

@@ -255,6 +255,9 @@ rust_task::yield(size_t time_in_us) {
         name, this, time_in_us);
 
     if (killed) {
+        if (blocked()) {
+            unblock();
+        }
         killed = false;
         fail();
     }

src/test/run-fail/linked-failure4.rs

@@ -1,5 +1,4 @@
 // -*- rust -*-
-// xfail-test
 // error-pattern:1 == 2
 use std;
 import std::task;
@@ -24,8 +23,8 @@ fn sleeper() {
 }
 
 fn main() {
-    let f = parent;
     let g = sleeper;
-    task::spawn(f);
     task::spawn(g);
+    let f = parent;
+    task::spawn(f);
 }