OverflowError: timeout is too large in test_agent_linux_utils

From jenkins test run reported in bug 1202055:

 Traceback (most recent call last):
  File "/home/jenkins/workspace/gate-neutron-python27/neutron/tests/unit/test_agent_linux_utils.py", line 62, in test_with_addl_env
   addl_env={'foo': 'bar'})
  File "/home/jenkins/workspace/gate-neutron-python27/neutron/agent/linux/utils.py", line 54, in execute
     obj.communicate())
  File "/usr/lib/python2.7/subprocess.py", line 754, in communicate
    return self._communicate(input)
  File "/usr/lib/python2.7/subprocess.py", line 1314, in _communicate
     stdout, stderr = self._communicate_with_select(input)
   File "/usr/lib/python2.7/subprocess.py", line 1415, in _communicate_with_select
     rlist, wlist, xlist = select.select(read_set, write_set, [])
   File "/home/jenkins/workspace/gate-neutron-python27/.tox/py27/local/lib/python2.7/site-packages/eventlet/green/select.py", line 79, in select
     return hub.switch()
   File "/home/jenkins/workspace/gate-neutron-python27/.tox/py27/local/lib/python2.7/site-packages/eventlet/hubs/hub.py", line 187, in switch
     return self.greenlet.switch()
   File "/home/jenkins/workspace/gate-neutron-python27/.tox/py27/local/lib/python2.7/site-packages/eventlet/hubs/hub.py", line 236, in run
     self.wait(sleep_time)
   File "/home/jenkins/workspace/gate-neutron-python27/.tox/py27/local/lib/python2.7/site-packages/eventlet/hubs/poll.py", line 84, in wait
     presult = self.do_poll(seconds)
   File "/home/jenkins/workspace/gate-neutron-python27/.tox/py27/local/lib/python2.7/site-packages/eventlet/hubs/epolls.py", line 61, in do_poll
     return self.poll.poll(seconds)
 OverflowError: timeout is too large