Add test for #783. Closes #783

Author: brson

src/test/run-pass/issue-783.rs

@@ -0,0 +1,25 @@
+use std;
+import std::comm::*;
+import std::task::*;
+
+fn a(&&_args: ()) {
+    fn doit() {
+        fn b(c: chan<chan<int>>) {
+            let p = port();
+            send(c, chan(p));
+        }
+        let p = port();
+        spawn(chan(p), b);
+        recv(p);
+    }
+    let i = 0;
+    while i < 100 {
+        doit();
+        i += 1;
+    }
+}
+
+fn main() {
+    let t = spawn_joinable((), a);
+    join(t);
+}