Swarming tasks error on exception when the swarming bot is unable to find the device logcats in the TearDown step.

ex.
E  107.166s Main  Failed to locate logcat for device 06be45b2003b9b9f
Traceback (most recent call last):
  File "/b/swarm_slave/w/irPmdMY1/build/android/pylib/local/device/local_device_environment.py", line 192, in TearDown
    with open(m.output_file, 'r') as infile:
IOError: [Errno 2] No such file or directory: '/b/swarm_slave/w/it94Qg9Y/tmp9Z6kFp/06be45b2003b9b9f_20160812T210836'
E  108.084s Main  Unrecognized error occurred.
Traceback (most recent call last):
  File "/b/swarm_slave/w/irPmdMY1/build/android/test_runner.py", line 1004, in main
    return RunTestsCommand(args)
  File "/b/swarm_slave/w/irPmdMY1/build/android/test_runner.py", line 822, in RunTestsCommand
    return RunTestsInPlatformMode(args)
  File "/b/swarm_slave/w/irPmdMY1/build/android/test_runner.py", line 943, in RunTestsInPlatformMode
    all_raw_results, args.json_results_file)
  File "/b/swarm_slave/w/irPmdMY1/build/android/pylib/base/environment.py", line 33, in __exit__
    self.TearDown()
  File "/b/swarm_slave/w/irPmdMY1/build/android/pylib/local/device/local_device_environment.py", line 207, in TearDown
    [m.output_file for m in self._logcat_monitors])
  File "/b/swarm_slave/w/irPmdMY1/third_party/catapult/devil/devil/utils/file_utils.py", line 29, in MergeFiles
    raise e
IOError: [Errno 2] No such file or directory: '/b/swarm_slave/w/it94Qg9Y/tmp9Z6kFp/06be45b2003b9b9f_20160812T21083