Fix keyboard interrupt in test driver.

tools/testrunner/local/pool.py

 #!/usr/bin/env python
 # Copyright 2014 the V8 project authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 from multiprocessing import Event, Process, Queue
 
 class NormalResult():
   def __init__(self, result):
     self.result = result
@@ skipping 116 matching lines @@
     # they empty the queue buffer.
     self.done.set()
 
     for p in self.processes:
       # During normal tear down the workers block on get(). Feed a poison pill
       # per worker to make them stop.
       self.work_queue.put("STOP")
 
     for p in self.processes:
       p.join()
+
+    # Drain the queues to prevent failures when queues are garbage collected.
+    try:
+      while True: self.work_queue.get(False)
+    except:
+      pass
+    try:
+      while True: self.done_queue.get(False)
+    except:
+      pass