fix whitespace in workerpool test, rm unused import

address Stu's comment.

Testing Done:
reran worker pool tests.

Reviewed at https://rbcommons.com/s/twitter/r/2144/

tests/python/pants_test/base/test_worker_pool.py

@@ -6,7 +6,6 @@
                         unicode_literals, with_statement)
 
 import threading
-import time
 import unittest
 
 from pants.base.worker_pool import Work, WorkerPool
@@ -22,6 +21,7 @@ def register_thread(self, one):
 def keyboard_interrupt_raiser():
   raise KeyboardInterrupt()
 
+
 class WorkerPoolTest(unittest.TestCase):
   def test_keyboard_interrupts_propagated(self):
     condition = threading.Condition()